A conversation I had with someone prior to rehearsing a duet in high school:
Me: Do you want to use the metronome to keep time?
Cellist: No, I don't like metronomes. They speed up.
Me: Really? All of them speed up, huh?
Cellist (starting to smile:) Yes, they speed up.
Me: That's a peculiar glitch they all have in common, then.