One time at a audition the other guitarist started a song 1/2 step above the rest of us, naturally I assumed it was me out of tune (before tuners that weren't oscilloscopes). I painfully tuned my guitar while playing lead and the song played on. As soon as I had a close tuning he realized he was in the wrong key and changed back. The bass player never even noticed, but the club owner did. We changed the name of our band the next day.