When you're on your iPod and you can't stick to one song for more than 30 seconds without switching the song.
Jack: "Hey dude, what you listening to?"
Jill: "I was listening to Hot N Cold by Katy Perry but now I'm listening to Burnin' up by the Jonas Brothers. I can only stay on one song for like 30 seconds!"
Jack: "You must have iPod syndrome!"