Bieber allegedly headbutted a man at a pre-GRAMMY party last weekend at Serafina restaurant, according to TMZ
, and cops are now investigating the incident as a possible crime. Bieber was reportedly "play fighting" with former That's So Raven
actor Kyle Massey at 2 a.m. Saturday, when he allegedly got upset at somebody recording him and refusing to delete the video. The "Baby" singer then allegedly headbutted the man -- prompting a person at the scene to call the police -- though Bieber left before deputies arrived.