About 10 years ago in high school I was playing in the big band. Apart from gigs at festivals and stuff, we'd play at school functions, including everyday stuff like whole-school assemblies, which were held in a big, echoey gym/hall. Anyway, we were quiet while some announcements were made. My bass was on, turned up, etc. I was having gut troubles at the time, and my stomach was growling and rumbling. I took my hands away from my bass, no longer muting the strings. My stomach rumbled, vibrated the bass, vibrated the strings, and it all came out the amp - LOUD! And it wasn't just string vibrations, it was just like an amplified stomach growl!
More recently I drank too much before a gig after a long day of traveling. In the third set, I actually fell asleep for a microsecond or two while playing some boring three chord song. Didn't skip a beat! Not sure if that was embarrassing, legendary, or just lame!