Sam Is on Trombone Rapper Gift of Gab and DJ Chief Xcel paired up as the Bay Area hip-hop duo Blackalicious (below, doing “Chemical Calisthenics”) more than two decades ago. And in the ensuing years, they’ve become as equally well-known for their energetic live performances as they have for their discography, which includes three acclaimed full-lengths filled with tongue-twisting rhymes like “Alphabet Aerobics.” A fourth LP — their first in 10 years — Imani Vol. 1, comes out next month. Bronx rapper Kool Keith began his music career as part of the Boogie Down’s eccentric hip-hop outfit Ultramagnetic MC’s in the mid-’80s before going solo in 1996. He’s since become known for his free-flowing, abstract (and dense) lyrics, a variety of musical personas, and a willingness to take chances. His most recent album, Time? Astonishing! (stream it below), a collaboration with Nashville producer L’Orange, arrived earlier this year. And on Thursday at Brooklyn Bowl, Kool Keith (below, performing “Poppa Large” for Paste magazine) teams up with Blackalicious for “Sam Is on Trombone,” featuring the Lucky Bears Foot Band.