Got a funny story here, copied it from an old thread, but it kind of fits.
We were in the middle of playing Cissy Strut > Soul Island, which is a long instrumental jam that we chose to open up our second set with. It gives our singer a little break (read time to remember to tune his freakin' mandolin). Well our guitarist, keyboardist, drummer, and I were grooving pretty good. I had just kicked on the q-tron and was getting ready to lead us into the transition, when all the sudden I hear a loud "Oh no!" come from my guitarist. A quick little note on this venue's geography. This venue has the single restroom directly to the left of the stage. It's actually tucked away nicely and directly beside our guitarist. Well all the sudden I hear our guitarist go "Oh no!" and I see his face. It literally looks like somebody had sucked all the color out of it. He just lifts up his guitar and puts it on the stand and then runs into the bathroom. Our vocalist, notices this, and quickly runs over to pick up his guitar, and proceeds to kind of just strum the chord. Well we're not sure if we should wait for our guitarist, or if we should proceed to transition into the next jam and start singling Soul Island. So our singer starts moving forward to the mike, so we decide to start into Soul Island. It's going ok, until about half way through we are overwhelmed with this hideous stench. Even people at the bar noticed it. Well on the final note as we end our song, the bathroom door blasts open and our guitarist comes out of there. Kind of walking on his tippy toes. Our guitarist had blocked the toilet and it was flowing out of the toilet and into the bar right beside the stage. Our guitarist is grinning. Everyone notices what's going on. He simply takes a bow and straps back in. We played in that stench for the rest of the night. Shortly after pretty much everyone left. It was hilarious.