In the 137th episode of “Seinfeld,” Jerry explains the concept of the Bizarro World, which originated in the Superman comics, to his friend Elaine. She has befriended Jerry’s polar opposite, who lives in a backwards replica of Jerry’s apartment and, unlike Jerry, is considerate and kind.

“Like Bizarro Superman!” Jerry says. “Superman’s exact opposite, who lives in the backwards Bizarro World. Up is down, down is up, he says ‘hello’ when he leaves, ‘goodbye’ when he arrives.”

Perhaps no other comparison is as apt for 2016. It’s Bizarro World, in which everything we’ve been told could never, ever come to pass actually, incredibly has happened.

Brexit. Trump. Polling as predictive, reality as agreed-upon, satire as obvious — none of the old norms hold.

When Julia Louis-Dreyfus won the Emmy last September for her portrayal of callow, cynical President Selina Meyer in “Veep,” she noted that the show, once a highly-exaggerated spoof of the American political system, now seemed an actual reflection.

“I think that ‘Veep’ has torn down the wall between comedy and politics,” she said. “Our show started out as a political satire, but it now feels more like a sobering documentary.” Louis-Dreyfus also told the Hollywood Reporter that if her writers lifted things that actual candidates had been saying on the stump, “we’d get notes back from HBO saying ‘It’s too broad, it’s too over-the-top.’”

Yet here we are.

The year began with the unexpected loss of David Bowie, who, we learned later, had been battling cancer for the past 18 months. That he kept his illness private — unusual in our over-sharing era — added to our collective shock.

After Bowie came more, one after another: Antonin Scalia, leaving a still-unfilled seat on the Supreme Court. Garry Shandling, Alan Rickman, Gene Wilder. Muhammad Ali, a folkloric American great. Elie Wiesel and Harper Lee. Fidel Castro, a Communist relic, at age 90. Leonard Cohen, who weeks before his death told the New Yorker, “I am ready to die,” then took it back days later.

“I think I was exaggerating,” Cohen told Billboard. “I’ve always been into self-dramatization. I intend to live forever.”

Cohen passed away a few weeks later, in his sleep, at age 82.

The passing of Prince in April, alone in an elevator at his Paisley Park estate, was, like Bowie’s, completely unexpected — even though in April, he fell so ill that his plane was forced to make an emergency landing, and he was rushed to the hospital.

Prince never addressed his ailment, but days later told fans that there was no cause for concern.

“Wait a few days” he said, “before you waste any prayers.”

As we learned after his death, this athletic performer, who looked decades younger than his 57 years, known by friends and colleagues as a clean-living Jehovah’s Witness, harbored a decades-long drug addiction that ultimately killed him.

The most cultivated celebrity images crumbled in 2016. Johnny Depp, known for the child-friendly “Pirates of the Caribbean” franchise, was accused of spousal abuse. After estranged wife Amber Heard posted incriminating photos and video online, Depp quickly settled for $7 million.

The epic Hollywood love story known as Brangelina — two A-listers besotted, wealthy, jet-setting-yet-nesting with a happily blended Benetton brood — was, in September, revealed to be a fraud when Angelina Jolie blindsided Brad Pitt with her divorce filing.

After a decade spent on lockdown, doling out only the most flattering information to the tabloids, TMZ suddenly had a direct channel to the gory details: Jolie accused Pitt of drug and alcohol abuse, of cheating with a co-star and with Russian hookers, and, most gravely, of child abuse.

Pitt was formally cleared of the abuse accusations in November, but the public now saw Brangelina for what it was: an epic construct, fictional as any Hollywood narrative.

Even George Clooney, a friend of Pitt’s, was shocked. “What happened?” he asked a CNN reporter. “I didn’t know . . . This is the first I’ve heard of it.”

At the 2016 Summer Olympics in Rio, 12-time medalist Ryan Lochte claimed that he and two teammates were robbed at gunpoint, at a gas station, hours before dawn.

“We were coming back from a friend’s house,” Lochte told the “Today” show, “and we got pulled over in our taxi, and these guys came out with a police badge . . . They pulled out their guns. They told the other swimmers to get down on the ground. They got down on the ground. I refused . . . And then the guy pulled out his gun, he cocked it, put it to my forehead and he said, ‘Get down.’ . . . He took our money.”

The resulting investigation found that Lochte and his friends had drunkenly vandalized the gas station’s bathroom and had been detained by security guards.

Lochte lost multiple endorsement deals worth $1 million and, as any figure of notoriety this side of Anthony Weiner does, promptly went on “Dancing with the Stars.” He was voted off in episode 8 and reportedly threw a fit.

“Ryan was actually telling people that he thought the show was rigged,” a source told Radar. “That everyone was out to sabotage him.”

“Rigged” was a big word in 2016: The economy’s rigged. The Democratic National Committee rigged the primaries in favor of Hillary Clinton, and chair Debbie Wasserman Schulz resigned because of it. “The system is rigged!” was basically Bernie Sanders’ entire campaign slogan.

Donald Trump said that if he lost the election, it would be proof the vote was rigged. At the final presidential debate, Hillary Clinton said that Trump’s refusal to accept the results of the election was “horrifying,” but is now with Jill Stein in claiming the election results were rigged — by Russian hackers and the FBI.

According to a YouGov poll released two weeks after the election, 42 percent of Democrats believe the results were rigged. Two weeks before the election, a Politico/Morning Consult poll found that 73 percent of Republicans believed the election would be rigged.

No matter who you voted for, the election of Donald Trump stunned everyone — including, it seems, Donald Trump, who, weeks prior, had son-in-law Jared Kushner explore the formation of “Trump TV,” his own cable-news network.

The markets, which most mainstream outlets, including the New York Times, predicted would “fall precipitously” in a Trump win, hit record highs within two weeks of his election. The Dow soared 800 points. For the first time since the 2008 crash, interest rates may go up.

Could our Bizarro World even mean a competent President Trump?

It has, after all, been a year of unprecedented happenings.

Not one but two multi-part re-examinations of the O.J. Simpson trial, 20 years later, captivated the nation and won critical acclaim.

Ten years after a DUI and subsequent anti-Semitic rants (“F–k the Jews . . . the Jews are responsible for all the wars in the world”), Mel Gibson is having an actual career comeback with “Hacksaw Ridge,” which he directed.

The NFL, long the most American and dominant of sports, saw viewership fall by 27 percent in 2016, according to Forbes. The Chicago Cubs, meanwhile, overcame “The Curse of the Billy Goat” to win their first World Series since 1908.

NASA finally made it to Jupiter. Bob Dylan won the Nobel for literature. Dave Chappelle came out of retirement. Kim Kardashian has been off social media for weeks.

Perhaps our weird 2016 isn’t an outlier but a harbinger, and proof that really, truly, anyone can be president. We did have it both ways: By popular count, we voted for our first female president by over two million ballots. By the electoral college, we voted for our first reality-TV star, an Internet troll who bragged about the size of his penis and talked about grabbing women “by the p—y.”

We are through the looking glass. We’re in Bizarro World. In the future, we ignore those mulling a run — however improbable — at our own peril.

It’s time to brace ourselves, America: Kanye, 2020.