The moment comes 38 seconds into the trailer. As a lavish party explodes around him, Leonardo DiCaprio’s perfectly coiffed, cocksure Jay Gatsby raises a glass of bubbly to toast his glorious self — launching a meme that is still going strong more than a decade after the Baz Luhrmann epic played its last movie house.

April 10 marks the 100th anniversary of the publication of F. Scott’s Fitzgerald’s seminal novel of excess and identity set against the Jazz Age — and while the book remains an English class staple, contemporary audiences are undoubtedly more familiar with the DiCaprio meme than the actual novel… or even the film that spawned it. Here’s a brief look at how a few seconds of screen time became a viral sensation.

DiCaprio’s immortal toast first entered the public consciousness on Dec. 20, 2012, when the second trailer for Luhrmann’s Gatsby dropped. The Warner Bros. film,...