One of the most beautiful things aboutis how it refuses to explain many of its most intrinsically Asian elements. That lack of training wheels is intentional: As director Jon M. Chu told me, "We didn't want to give people an excuse to think of this world as some kind of obscure, exotic fantasyland -- this is a real place, with real culture, history and tradition, and instead of just giving them answers to their questions, we want them to have conversations."The movie's Singapore-specific local color and broadly Asian cultural nuances are indeed fairly Google-able, and can readily be contextualized through polite discussions with actual Asian people. But there's one scene in particular that has been resiliently enigmatic to audiences of many backgrounds, both Asian and non-Asian... and it's a pivotal one:That's especially true for fans of the book, who won't recognize it -- it's original to the movie. It was inserted in part because Michelle Yeoh, who delivers an amazing steel-and-silk performance as the movie's main antagonist, refused to play the stock, villainous tiger mom from the book. This scene provides her with critical impetus toward her eventual redemption.But it's also true for people who don't understand the complex rules of the game, which aren't intuitive and are often different depending on region of the world. So here's a quick primer on the game of mahjong itself, as well as its significance to the film in that pivotal scene. Spoilers abound starting here, so if you haven't yet watched the deliriously warm and funny movie, crawl out from under that rock and see it before reading further.A quick primer on mahjong itself. A fast-paced, rummy-style game in which four players attempt to form sets of three or four matching or sequenced tiles, it's a hugely popular game not only across Asia, but around the world. Its origins are Chinese: all the way back in 1927, about a century after the game was invented, the Chinese scholar and essayist Hu Shi complained that mahjong was so popular that it had become China's "national pastime" — equivalent to baseball in America and cricket in England, calculating that the millions of games of mahjong played each day by Chinese were the equivalent of four million hours of wasted time a day.But most Chinese don't see the game as "wasted time." In fact, despite his grousing, Hu himself was an inveterate player who spent many an evening tossing the tiles. Mao Zedong himself once said the game should not be underestimated — because "If you know how to play it, you'll have a better understanding of the relationship between chance and necessity. There's philosophy in mahjong."In the movie, Rachel Chu, the protagonist brilliantly depicted by Constance Wu, is an economics professor at New York University who specializes in game theory (mandatory disclosure: Constance plays my son Hudson Yang's mother on the ABC television show). Her specialty was in no small part inspired by her childhood training in mahjong. As she says in the movie: "My mom taught me how to play. She told me mahjong would teach me important life skills: Negotiation, strategy, cooperation."She ends up utilizing all three in the game she undertakes with her nemesis -- and prospective mother in law -- Eleanor Young, played by Michelle Yeoh.When the scene begins, Eleanor has thrown a huge monkey wrench into the gears of Rachel's future with her son Nick (newcomer Henry Golding, who apparently bathed in suave then rolled in charm before each of his scenes). She has hired a private investigator to dig skeletons out of the Chu family closet, revealing that Rachel's mother isn't a widow as she's claimed, but a single mother who became pregnant with Rachel after an illicit affair, then fled China and her enraged, very much alive spouse for the safety of America. Shady!The revelation makes Rachel persona non grata to the Young family matriarch, Nick's doting grandmother (the eternal Lisa Lu), and Nick is banned from spending any further time with her.But Nick won't have any of it, and chooses to propose to her anyway.The mahjong scene begins immediately afterwards. Rachel invites Eleanor to meet with her at a mahjong parlor — a gambling house frequented mostly by working or middle-class older folks who rent tables by the hour. This one is less seedy than most; many of them are in smoky, darkened basements, but this one is airy, well lit and silent except for the persistent clacking of tiles.When Eleanor arrives, she takes the open seat across from Rachel, and is offered the role of dealer — the "East" seat. The four seats in mahjong are named after the compass directions, which plays an important role both in the rules of the game and in the symbolism of the scene. Eleanor, in the role of the "East," representing Asia, is the player in control. Rachel, sitting across from her, represents America -- the "West."The tiles have already been "washed" (e.g., mixed face down, like shuffling cards) and laid out in "walls" -- rows of 36 tiles stacked in two tiers. As dealer, Eleanor deals out the "hand" of tiles: first, she rolls the dice, and gets a 4 and a 6. She counts out to ten counterclockwise around the table, then counts to ten along the "wall" in front of the player picked, "breaking the wall" at that point and takes four tiles, with each player following suit until they have 12 tiles. A last tile is picked to make 13, and this is the players hand.This is when the game truly begins. Players in turn pick up tiles and discard them, in an attempt to turn their hand of 13 tiles into four sets of three matched or sequenced tiles, plus an "eye" -- a matched pair. Altogether, a winning hand requires 14 tiles, and victory must be declared after taking the last and final 14th tile.Mahjong is played in multiple rounds, with each player taking turns as East (the dealer) once during each round, and different patterns of "winning" hands have different scores. Randomly completed sets of matches and sequences might score just a single point, or none at all; hands with only matches (called "pong") or only sequences ("chow"), or all of one "suit," or containing certain honor tiles, will score more. Usually you can't declare mahjong until you have at least three points in your hand, so players may sit on "complete" hands and attempt to upgrade them, only ending the game when when they've maxed out their score — or to end the game before another player seizes victory.So communication -- and negotiation, and strategy, and even cooperation — are far more critical in mahjong than in most card games. Watching what your opponents discard as well as the completed sets they lay out in front of them — when one steals a tile that another player has discarded, one must expose the completed set — is the key to understanding what each is attempting to accomplish.Early in the scene, Eleanor completes a "pong," that is to say, she picks up a discard (a nine of circles) that Rachel has laid out, then lays out a matched set of nine of circle tiles. This is critical because it shows to Rachel that Eleanor is likely seeking to make a winning hand that is composed of "pong" matches. Eleanor tells Rachel that her mother taught her how to play too.At this point, we lose track of the tiles being discarded while the conversation continues. Rachel asks Eleanor why she didn't like her from the very beginning — even before her family history was revealed. Eleanor responds with a disquisition on the difference between Asians and Americans, noting how even though Asian Americans look Asian, they are American at heart. Referencing a Hokkien term that means "our kind of people," she says that Asian Americans are not "." Remember, in this game, Eleanor is trying to create a winning hand that is all matches -- an "extended family" that's metaphorically composed of "kaki lang."The camera cuts back to the discard tiles to show a number of discarded bamboo tiles (the three, the six, and the nine) as well as two wind tiles --, the East wind, and, the West wind.Discarded bamboo calls to mind a frequently used term for Westernized overseas Asians, this one Cantonese: "," which literally means "empty bamboo." It's a slang term that's the Chinese equivalent of the Asian American term "banana" -- yellow on the outside, white on the inside -- cited earlier in the film by Peik-Lin Goh (the frenetically hilarious Awkwafina). The "empty" bamboo tiles are scattered alongside the tiles for East and West, not truly part of either. The discard tiles have become a portrait of Eleanor's perception of Rachel.At this point, Rachel drops the bomb on Eleanor that Nick proposed to her, telling her that he said he'd be willing to walk away from everything, his family, his family's wealth, to be with her. Right as Rachel is saying this, she draws the most important tile in the game: An eight of bamboo.The number eight is symbolically of huge importance to Chinese; it resembles the character for fortune, and is considered a sign of wealth, prosperity -- and happiness. It's why so many Chinese license plates, phone numbers and even street addresses contain eights. Monterey Park, the first city in the San Gabriel Valley to become a suburban destination for wealthy Chinese, was considered a particularly propitious place to live because it had an 818 area code.While an eight doesn't have special value in the game of mahjong, we see that the eight of bamboo is also the one tile Rachel needs to complete her hand -- a hand full of bamboo melds and honors tiles. This is a winning tile for her. But Rachel knows something else, based on her observation of how the game has played out (remember, she's a game theory professor!): It's Eleanor's winning tile too.She then discloses to Eleanor that she turned Nick down. Eleanor is dumbfounded. "Only a fool folds a winning hand," she says, referring to Nick's proposal.This is important, because in the very first scene of the movie, Rachel demonstrated through a poker game with one of her T.A.'s that to be successful in any game where psychology and choice are a factor, you can't play "not to lose" -- you have toRachel explains: when it comes to her marriage with Nick, Eleanor has guaranteed there's no winning outcome for them. Nick choosing Rachel means he'd lose his mother and his family. Nick choosing his family means he might resent Eleanor forever — thus losing his mother anyway. Lose-lose.So she decided to seize control of the situation, and choose for him. But she doesn't want it to happen without Eleanor knowing exactly why it's happening and what Rachel is giving up to make it possible.She tells Eleanor that she knows Nick will eventually find someone else, someone that his family approves of — that's what every generation of Youngs has done before him, after all. And while her own heart will be broken, as she says, she loves him so much that she is willing to suffer, if it means that Nick will keep the thing that is at the heart of Asian culture, and of his story: his family.That's when Rachel throws the eight of bamboo out as discard --, knowing that Eleanor will pick it up and declare victory. (A sidenote: when Rachel does so, the player to her right moves to take it, but is overridden by Eleanor, because -- as Rachel knows -- Eleanor has control: If you're making a pong pickup to form a winning hand, you have the right to take a discard over someone who's just picking it up to make a single set.)While this happens, she explains that when Nick finds the proper match in the future, she wants Eleanor to understand that the only reason it occurred was because a "poor, raised by a single mother, low class immigrant nobody" -- Rachel -- made it possible.She then reveals her hand which would have won, making it clear to the whole table what she's done, and walks away. In the course of this game, Rachel has demonstrated to Eleanor three critical things: the first is that she loves Nick enough to put his future ahead of hers. The second is that she understands that family should always come first — something that Eleanor suspected she didn't comprehend as a jook sing, "banana" Asian American. And the third is that Rachel is a strong, self-sacrificing, courageous and hella-smart badass... kind of like Eleanor herself. Instead of "never being enough" for Nick, a line Eleanor uses to surgically destroy Rachel in an earlier scene, she's most likely exactly what Nick needs.Knowing all of this context isn't necessary for the scene to work! But it certainly adds depth to it, doesn't it?When asked about the mahjong scene, director Jon M. Chu told me: "For the mahjong scene, never thought we'd have to explain it," and laughed. "I wanted it to be very specifically choreographed, and obviously, for it to happen that fast is almost impossible. But I wanted to intercut the game with the conversation, so it was critical for them to know exactly what they were doing at every moment. We got a mahjong expert — basically a gambling addict! — to help choreograph that game, to make it authentic."In case you're wondering, here's Rachel's winning hand, and the scoring she would have gotten if she'd gone out with it instead of discarding her lucky eight of bamboo:An eye of "Red Dragons"; a matched set (pong) of North winds; a six, seven, eight sequence of bamboo, and two pong, one of fours of bamboo and the other of threes of bamboo.She also had two "bonus tiles," which can entitle you to extra points. The first one is a Winter tile -- which is associated with the player sitting in the fourth seat -- and what appears to be a chicken tile (Singaporean mahjong sets have a unique addition of four animal tiles: the cat, centipede, mouse and chicken.Of course, the chicken is meaningful in the scene and the movie because, as Peik-Lin points out, Rachel and Eleanor are engaged in a game of "chicken." In this scene, Rachel proves that she won't be the one run off the road. BUK BUK, BITCHES!If you're really curious, here's how Singaporean rules would have scored Rachel's hand:Half Flush (hand composed of all one suit plus honors): 2 pointsFully Concealed Hand (no pong or chow sets revealed in front of her): 1 pointAnimal tile: 1 pointShe scores no points under Singapore rules for the flower, since it's associated with the 4th seat, which is neither her seat nor the "prevailing" seat (East is dealer in this hand).That's 4 points, out of a typical maximum per round of 5. Every player would pay her $16, for a total of $48 for the hand. Singaporeans play a low-stakes version of mahjong!