Offensive jokes, an insulting slang dictionary, the world's largest multilingual swearing archive of 165 languages, random insult generators - you'll find them all here.

http://www.insultmonger.com

in czech, if you forget to close the door behind you, people will ask you
mas v prdeli stromecek
which means have you got an xmas tree up your arse

but i liked 'did you shit in the cinema'