Chris Brown and Justin Bieber -- We Roll Deep ... Most of the Time

Chris Brown and Justin Bieber hanging out on a Saturday night sounds like a recipe for disaster -- and it was ... if you call Justin eating it while roller skating a disaster.

No double cups or disloyal hos were in sight when JB and CB got their roll bounce on at Breezy’s “Skate Jam” outside L.A. the night before the BET Awards.

Brown seemed to have no trouble, but the Biebs took a tumble (barely captured by the photog).