DAVE MATTHEWS BAND FANS.
Can't stand them. They are the most annoying pseudo-intellectual pot smoking sheep out there. I think DMB sucks with or without his fans, but what really elevates my annoyance with that band is their fans.
Runners-up: Van Hagar fans, die-hard Metallica fans who still like the current version of Metallica, die-hard Phish fans (bunch of degenerates), die-hard KISS fans.