In England there aren't that many words for someone's arse or whatever. But, its if its arse in relation to names for homosexuals, there's loads. For instance, no-one uses (or even knows) the word "batty", but if u use the word "batty boy" ( which means a gay), everyone knows the word.
How about some Chinese: 屁股 (pi gu), 臀部 (tun bu), 后方 (hou fang), 后部 (hou bu), 尾部 (wei bu) And of course, what we enjoy doing: 打屁股 (da pi gu) -- spanking (do not "da" any other synonyms please....)