Sexual act usually performed by two or more males where each participant attempts to insert the largest object into their anus. Size is typically judged by length though usages of average width and width at widest point have also been recorded.
(From SE Asian 'New English'.) When one's offer of help has been rebuffed, to take offence and thereupon actively endeavour to worsen a situation (out of spite).
I tried to help Brian out, but he was just really rude to me. So I decided to break my finger (off) in his butt.
If he doesn't appreciate all my advice and hard work, I will just break my finger (off) in his butt.