1. slang To put forth a great deal of effort. I've been busting a gut trying to get a passing grade this semester, so failing by two measly points is incredibly frustrating. Don't bust a gut trying to please these people—they'll never appreciate it.

2. slang To start laughing suddenly or uncontrollably. To convey this meaning, the phrase can also be expanded to "bust a gut laughing." The kids busted a gut when the clown fell down on stage. I nearly bust a gut laughing at that comedy show—I could barely breathe!

3. To react furiously and/or violently, to the point of losing control of one's behavior. Mom totally busted a gut when I told her I had failed math. Don't bust a gut, it's just a tiny scratch on the car.