I haven't met any musicians, but I've met MLB players.
Tim Hudson (he lives in the next town over from me, his son plays in the local little league), Johnny Estrada (he trains where I used to take baseball lessons), Rodney richardinson (played MLB for only a short time, mostly played minor league, the guy I took baseball lessons from for about a year and a half)
I got all their autographs on a wooden baseball bat. I forgot my glasses one day and Rodney said he bet I would have a bad day of training, and if he lost he'd give me a wooden bat for free.
He lost >:D