A person who pretends to like the same bands & artists that your friends like just to get accepted into your crowd & mingle with you, but when they are alone, they listen only to their old shameful bullshit music in the closet to avoid embarrassment.
"Cornelius is a Closet Bandito! He pretended to like our favorite bands & dress up cool just to hang with us. He just pretends to listen to Uglyhead. This whole time, he's been flailing his arms & dancing to Peyton Parrish in the closet!"