Not literally a pain in one's anus
or gluteus maximus
, though either would count.
Something quite annoying, but not as bad as a ballache
, which would also be expected to last longer.
People, Places, Things: it doesn't matter. Often shortened to just: a pain.
Was that your uncle
Yeah. What a pain in the arse.
Well, i wasn't gonna say anythin, but...
You wanna meet my Dad
! What a ballache
, he's coming over, time for a cool sharp one