Toby Fox’s “Megalovania” may be known as a five-year-old video game banger, but the meme behemoth actually has a more layered history.

The first iteration of the track, which existed long before Undertale, was released in 2009. Ten years later, the song is still kicking around on Gen Z homebase TikTok, the social media app where music reigns supreme. In fact, the basic tenets of the song’s popularity within video game spaces are perhaps the single best blueprint for understanding TikTok’s humor as a whole.

Famous for its association with Sans, the funky Undertale skeleton who has been memed to hell and back, “Megalovania” was a consistent presence in internet game culture of the late 2010s.

But the track, which was written by Undertale creator Toby Fox, existed before it was associated with a hoodie-wearing skeleton in a video game. Originally penned by Fox for his 2009 ROM hack of Earthbound, the track has appeared in a smattering of other places: it was a part of the sixth installment of the Homestuck soundtrack (stylized as “MeGaLoVania”), gained infamy through Undertale, and is now a part of the Super Smash Bros. Ultimate OST.

Undertale, which was released in 2015, pairs “Megalovania” with Sans’ daunting boss battle. The showdown only occurs in a “genocide ” playthrough where the player kills every creature they encounter in-game. “Megalovania” is by far the most infamous song off of the soundtrack. Part of the popularity is due to the fact that the track is an evergreen bop. It also helps that Undertale and its fanbase were launched into infamy — the game has been one of Tumblr’s five most talked-about video games every year since its release.

And popularity begets reinterpretations. “Megalovania” first received the standard remix treatment in the wake of its new video game release in late 2015, a rote phenomenon that eventually morphed into mashups with songs like Daft Punk’s “Harder Better Faster” or “Renai Circulation,” the fourth opening theme of Bakemonogatari that’s also popular on TikTok.

What started as variations on a great track quickly turned into meme fodder. “Megalovania” started popping up everywhere on the internet. Many of these early covers and remixes of the song were intended to be nonsensical shitposts — like these mid-decade airhorn and kazoo covers, for example — in an attempt to take the song less seriously.

But, things haven’t slowed down in recent years. Take a January 2019 mashup of “Megalovania” and Owl City’s “Fireflies,” or this remix that pits the single against 2018 League of Legends K-pop hit “POP/STARS:”

These more serious remixes and mashups made “Megalovania” both recognizable and funny.

At the same time, Sans from Undertale was also earning his place in meme culture. People in the Undertale fandom drew him and relentlessly quoted some of his more memorable lines, like “You’re gonna have a bad time.” Eventually, it became a trend for people to trick others into accidentally listening to the track while interacting with seemingly innocuous content on the internet. Meme archive website Know Your Meme attributes the origin of this bait-and-switch tactic to a Family Guy parody tweet made by Twitter user @conkface; since then, it’s taken off.

Five years later, “Megalovania” has become an inescapable presence on TikTok, where users slide it in at the ends of videos, mash it up with viral TikTok sounds like Sub Urban’s “Cradles,” or play it on the cello in full Waluigi cosplay. It helps that Megalovania sounds like a TikTok song, both in its repetitive riffs and melodramatic, chiptune-esque palette. Those qualities play out well on TikTok because they make sounds memorable and quirky; repetition provides a catchy but un-intimidating canvas for trends like dance or posing challenges (see: “Junko posing.”)

Dan, a music-focused TikToker and YouTuber better known by his handle @dein0mite, frequently worms “Megalovania” into his content. He found his niche on TikTok covering popular sounds on piano and putting out mashups of popular memes; “Megalovania” is like his calling card. “I’m not 100% joking when I say that [“Megalovania] is a bit of a curse,” he said over email. Citing Megalovania’s iconic melodies, which “fit so well into anything and everything ... [it’s] hard NOT to return to it!”

However, mashup culture on TikTok extends far past joining two popular meme tracks together. “[Mashups are] essentially the perfect recipe for original content, because you’re taking what would be regular trends and giving it your own spin,” Dan said.

Once a tune or clip gains prominence — like “anime is an important part of our culture” or n04h’s “Carless Gambino” remix — creators can count on the viewer’s familiarity with previous viral jokes to make entirely new gags. Songs are remixed, riffed, and reinterpreted until they take on entirely new forms on TikTok.

“Megalovania” lives on as fodder for bait-and-switch jokes. “Rickrolling” is perhaps the most infamous bait-and-switch meme, but the most important part is that these jokes lull you into a false sense of security only to hit you with a “gotcha!” moment. For audio jokes, that means beginning with a familiar sound or video clip before suddenly switching over to something else that’s still familiar but unexpected. For example, “Megalovania” has popped on TikTok at the tail end everything from “Baby Shark” melodica covers to chopped up Kesha tracks.

It’s the TikTok equivalent of a pun, where the aim is to get an amused groan out of the audience. But while some songs may fade away, “Megalovania” and its innate meme-ness allows it to continue being a staple for those who are extremely online. Take, for instance, Sr Pelo’s especially bonkers parody cover “Mogolovonio.”

“Megalovania” wasn’t hailed by music critics as one of the best or most defining tracks of the 2010s (no shade!). However, few other tracks made as definitive of a footprint on digital culture in the 2010s, and we can see that by sheer virtue of its meme persistence. While it may not have broken into the pop zeitgeist in the same way as other tracks like Lil Nas X’s “Old Town Road,” for a new decade of hitmakers who are using TikTok to launch their music careers, memes matter just as much as the charts they’re gunning for.

“Megalovania” makes a strong case for measuring the success of a song not by its chart history, but by its ability to be continuously reinvented.