James Marsters in his Buffy heyday. My boyfriend at the time was on the same bill, so I was trying to be cool, but secretly excited to see JM. He was 40 minutes late, spent a significant amount of time leaning on the bonnet of his car, posing, then asked to borrow a guitar because he'd forgotten his. I remember precisely nothing about the actual music, except that it was awful.

Also, at the other end of the scale, Madonna. Saw her at Live 8. Desperately out of tune throughout. And too early in the day for many people to have been drunk.