What is it: A popular subgenre of erotic cinema that is all about clowns getting naked and getting it on.
Why it's dumb: Clowns are not only scary, but they're like anti-Viagra. There are no clowns in hell, because they make Satan cry lava tears. Clown porn is dumb because you can't take it seriously, unless one is chasing you with an axe.
Alternative kink: Regular ol' porn where cartoonish professionals fornicate in grotesquely unrealistic ways.