A test of will power, courage, fortitude, etc. Rarely does it involve any physical strength or skill, instead being an almost entirely mental challenge. First heard in the US Army, but has spread through usage amongst veterans.
Jumping off the cliff at night, into the darkened water, with the pretty girl watching: it's a gut check. See what you're made of.
by Trail March 07, 2005
Gut check was originally a tennis term to describe a player pausing a moment to think about what just happened by closely examining and possibly adjusting his racquet strings. Back in the day strings were made of cat gut, commonly refered to as gut. This usually occurred after a great shot by an opponent. As with so many terms it has become popular to describe something very different.
Tennis commentator; " ...after that passing shot by John , James looks like he's taking a gut check"
by Whackdad May 09, 2015