Ah, l'Amour (1995)

In this clever and over-the-top satire of romantic rituals, a cartoon pickup artist is violently torn apart by the women he courts. Don Hertzfeldt's first student film, he plays the part of a mentally unwell animator who's losing his grip within his own movie; an idea he'd later revisit in other early "meta" shorts "Genre" and "Rejected". Despite being produced at the age of 18 and not intended for exhibition, HBO named it "The World's Funniest Cartoon" in 1998.