means your shitter, unlike all these yankees are saying, it is not a way of being polite. ass isn't swearing, arse is, fuckin ass, its arse simple as that. ass = a donkey
backside, bum etc. (Not ass. ass is an animal, not your backside, ass was used by americans only because their forefathers hadn't got the guts to say arse)
Somewhat goofy name for your butt. It is how many people in many countries refer to their ass. Only cool when said outside of the U.S., when used by an American it sounds stupid because they think saying arse makes them seem cute or intelligent. I can't imagine why.