I remember at the last Jonathan Coulton/Paul and Storm show, where I know the performers were distracted by the guy in the graphic equalizer shirt. And I think the other shirt that threw them was the pong shirt. Or maybe it was the Wi-Fi detector shirt.
Whichever it was, they were flipping out at the dancing lights being worn by certain members of the audience.
Now, I give a warning to them and to all the other pop culture/geekcentric musicians: ThinkGeek now has an electronic drum kit shirt.