Ronnie Rugburn

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 Axel Axe, Igby Stallion, and Thrash.

The bouncer's list has him as "Robbie Rugburn"; we're guessing the bouncer isn't very detail-oriented.