bust a gut

/B AH1 S T AH0 G AH0 T/
verb
  1. 1

    To work or try very hard.

    โ€œI had to really bust a gut to get it done by the deadlineโ€

  2. 2

    To develop a pain in the side from laughing hard.

    โ€œSomething about the way he said that made me just bust a gut: I practically died laughing!โ€

Source: https://en.wiktionary.org/wiki/bust%20a%20gut