Night of the seal (1974)

In La Nuit du Phoque ("The Night of the Seal") they "decided to try everything imaginable"; the 41 minutes are packed to the brim with wild and utterly incomprehensible visual and textual shifts, including special effects, graphic but sensual love scenes, a hilarious Busby Berkeley-style "revolutionary ballet", a superb avant-garde gay cabaret number sung by Philippe Danton – imagine a cross between Rocky Horror and the Trout Mask era Magic Band – and any number of absurd cameos (I particularly like the surprise appearance of Sir Isaac Newton, who scares the shit out of some kids playing in a local park). As a period piece La Nuit du Phoque is unbeatable, and it alone would make an impressive bonus.