I'm sure there are other threads on this subject, but it can't hurt to start a new one, as i'm sure many of us have messed up at one time or another.
This one moment from my gigging experience has been coming back to me lately (I just mentioned it in a different thread), and it's the type of thing that even just thinking about it now makes me cringe, even though it was from a couple of years ago.
I was debuting a new project, which was a three piece funky jazz combo, which later grew to include a guitar and small horn section. We were playing an outdoor show on the fourth of July, and it was stressful from the onset with a late sound guy and a bit of nerves. There were only a couple hundred people there at the most. We never really caught our groove, and at the end of the set we played Stevie Wonder's Sir Duke. Our keyboardist didn't have the skills to nail the bridge breaks, so it was all on me and the drummer, and i'm also singing the song which is a bit out of my range, but I can do it justice if i'm feeling comfortable. At one point I totally blank out during one of the breaks, and literally just stand there for a second. It was the kind of err that was pretty noticeable from the crowd, i'm sure (though much worse in my memory i'd bet). I then proceeded to finish the song rather poorly, and generally it was my worst stage moment ever. In retrospect it was a bad idea to do the song at that point, but what do you do....
Later we did many fine renditions of the song, although that band never did get super tight. I swear, though, thinking back to it will continue to make me shake my head for some time to come.
This one moment from my gigging experience has been coming back to me lately (I just mentioned it in a different thread), and it's the type of thing that even just thinking about it now makes me cringe, even though it was from a couple of years ago.
I was debuting a new project, which was a three piece funky jazz combo, which later grew to include a guitar and small horn section. We were playing an outdoor show on the fourth of July, and it was stressful from the onset with a late sound guy and a bit of nerves. There were only a couple hundred people there at the most. We never really caught our groove, and at the end of the set we played Stevie Wonder's Sir Duke. Our keyboardist didn't have the skills to nail the bridge breaks, so it was all on me and the drummer, and i'm also singing the song which is a bit out of my range, but I can do it justice if i'm feeling comfortable. At one point I totally blank out during one of the breaks, and literally just stand there for a second. It was the kind of err that was pretty noticeable from the crowd, i'm sure (though much worse in my memory i'd bet). I then proceeded to finish the song rather poorly, and generally it was my worst stage moment ever. In retrospect it was a bad idea to do the song at that point, but what do you do....
Later we did many fine renditions of the song, although that band never did get super tight. I swear, though, thinking back to it will continue to make me shake my head for some time to come.

So the hole in the song was HUGE!!!!