Have you considered a spam forum? It doesn't have to be one full of forum games like "avatar above you" or something, it could just be a place to make forum posting tests and experiments, or for anyone to make stupid hilarious threads about nothing. At PureZC, a major resource site for Zelda Classic (Zelda 1 editor), we use a forum like this mostly for showing off bizarre, hilarious humor (which quite a few people here have, I know.) Said place still keeps rules of conduct against inappropriate content, flaming, etc. but rules regarding spam, double posts, etc. are all waived. Nobody gains any post count by posting in it either, so it's no fast pass to anything.