The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with bust a gut
burst a gut.
Exert one-self to the utmost. For example, He was busting a gut trying to please her. This hyperbolic term alludes to hurting one's mid-section through physical straining. The first slangy term dates from the early 1900s, the variant from about 1700. For a synonym, see break one's ass
Explode with strong feeling, especially laughter or anger. For example, Gene almost bust a gut laughing, or The foreman will burst a gut when he learns that the machine isn't repaired. The former dates from the late 1800s, the latter from about 1940.