Verb
(slang) To work or try very hard.
I had to really bust a gut to get it done by the deadline
(slang) To develop a pain in the side from laughing hard.
Something about the way he said that made me just bust a gut: I practically died laughing!
I really worry about these political people that have no personal life. If there's nothing that's lovely, and if there's nothing that's just ephemeral, that you can just lie on the floor and bust a gut laughing at, then what's the point? Arundhati Roy