Fan subs gone wrong = lolzorz http://www.slightlywarped.com/crapfactory/curiosities/2009/fan_subs-Gone_wrong.htm
Some of those aren't even mistranslations! That talking horse-creature at the bottom of the list (second to top in Giggadee's post) is from a particularly nasty Hentai anime, and you can guess what's happening to the poor heroine in that scene! The Santa scene from Hayate no Gotoku is also a correct translation of a scene where that is an in joke about Hayate always being poor. I even remember watching that episode... I loved the cow's translator's note! Who would have known otherwise?