I remember the time I saw Bill Dickens (aka "The Buddha of Bass") play as part of a Peavey guitar/bass/drums clinic... I coudn't even look at my bass for 3 days. But after that I started trying some of the ideas he was talking about, and I'm probably a better bassist for the whole experience.

Other than that, I've had a few crappy nights. One night I was sick as all hell. I went home from this open mic early and went to bed- for three days straight. Anyway, I was really off- I screwed up Johnny B. Good very badly. So I blindly wandered off the stage and some guy comes up to me and asks me to play in his band and all I can think is "I just ____ed up Johnny B. Good... what does he want from me?" So like I said, I went home and spent the next 3 days in bed wondering if I was going to vomit or leave some skid marks.

But if you can get back on stage after a horrible and public humiliating experience, you're well ahead of the game. It prepares you for far more traumatising events later in life like nothing else can.