Hilarity is a rarity in those snoozy hours before your fave indie-rock band hits the stage, so when Baltimore-raised rapper/beat junkie/lifetime adolescent Cex is on the bill, it’s worth the trouble to arrive early. The self-styled “World’s No. 1 Entertainer” (Rjyan Kidwell) prefers to operate in a minimalist tableau—his tools are a laptop, a microphone, some class-clown charisma, and a skinny bod that’s sometimes covered only by a pair of underwear. But the lyrical universe of Cex is an ever-expanding cartoon network of smart-kid vocab, booty-bass clichés, self-annoyed analysis, hazy video-game memories, and zit-popping excitement. Like Jon Spencer, Cex is aware of the silly semiotics of his situation, but he dishes out the goods nonetheless. With glitchbeats and freestyles, he’ll try to upstage indie synth-pop supergroup the Postal Service and Bazhena at 8:30 p.m. at the Black Cat, 1811 14th St. NW. $8. (202) 667-7960. (Joe Warminsky)