A poser. Someone who goes to a "jamband" show yet doesn't know anything about the band, goes to the show because its deemed cool, has subwoofers that play 50 Cent all day in their SUV, wears the stereotypical hippy clothing, and makes fun of people who talk about 'positive vibes' and 'positive energy.' This describes, in essence, 95% of all Widespread Panic fans and also would be appropriate terminology for 80% of the crowds at Phish shows from 1999 and on.
"Dude, what is Todd doing at this Phish show? That jackass wears polo shirts with flipped up collars and yet today he has flip flops on with patchwork pants and a retro Dead shirt on from 77! Todd wouldn't know good music if it bit him on the ass. What a custie!"