hi,
today i wrote a letter (to an old aquaintance, whom i don't know very good), in which i wanted to describe a situation, where someone laughed VERY intensely - and because my english is kinda bad, i googled for a funny idiom. i found & used 'he laughed his ass off', which was described as 'slang-idiom'. after i sent the letter i suddenly found another description, saying that this is not colloquial or slang, but vulgar! this shocked me a lot, because i wanted to be funny, and the use of slang-language is really ok for me - but i did NOT AT ALL want to be vulgar! so i feel very embarrased now.. can you ease my sorrow - or NOT? 
thanks a lot for your help!
an abashed girl