Make the Win/Fail bumons at the end of each post do something other than add, subtract and store that number in a database. Such as being able to search for posts by their amount of win or fail.

Alternatively make it like a vBulletin rep system (yes, I know rep is usually horridly abused ie. nig rep).

Third alternative auto collapse the a post below a certain level, something along the lines of these 3 would encourage most user to use it properly…when I say most users I know some are still going to abuse it either way.

Finally, incentive always works. And it doesn’t even have to be high scale and at huge monetary loss to Crotch Zombie. The person with the most winning posts at the end of the month could get 2 free BP, a poster of the month type E-Peen, something. Just something that encourages people to make funny, unique, interesting posts and actually thinking them out before they just go tl;dr and post dragons.