Recent arrival to the Rock & Roll Underworld in the "Guitar of Rock" episode (17 March 2014) of Regular Show.
After Benson breaks a Flying V guitar signed by Bruce Rock, he, Mordecai, and Rigby (disguised as Max Amps, Zander Mercury, and King Pluto) have to go to the Rock & Roll Underworld for a new autograph.
Other recent arrivals (according to the bouncer's guest list) include Robbie Rugburn, Axel Axe, and Thrash. We later see a "Ronnie Rugburn" and a "Crash"; we're guessing the bouncer isn't very detail-oriented.
His name is likely inspired by Guns 'n' Roses frontman Axl Rose.