The EDM Dictionary: B2B (back-to-back)
In the dance music world, B2B or b2b indicates that two DJs will be performing onstage at the same time. This is indicated on lineups as “[DJ 1] b2b [DJ 2].” B2b is shorthand for “back-to-back,” so “Skrillex b2b Diplo” can be read as “Skrillex back to back with Diplo.”