You can't be vain and funny. Humor is throwing yourself into something at an extreme rate. Vein is poised. Vain is appealing to the masses. Humor is showing that we all share the same humanity. Vain is being out of reach. Humor is an ugly man's sport. They are able to contort their faces. They are able to let themselves jiggle. 

The problem is being beautiful feels good. You can just sit there. And feel the rays of adoration wash over you. 

Funny is sprinting. Throwing yourself into doors. Farting into a loudspeaker. Toot! Toot!