Timothy J. Blair, better known by his stage name Tim Dog, was an American rapper from the Bronx, New York, who rose to notoriety during the early 1990s with his debut LP Penicillin on Wax and the diss track "Fuck Compton". Tim had already appeared on songs with the Ultramagnetic MCs and went on to form a duo, Ultra, with member Kool Keith. "Fuck Compton" appeared in XXL magazine's "Top 25 Diss Tracks of All Time" and earned Tim Dog critical acclaim from progressive hip-hop producer Blockhead, who said Tim Dog's "The Dog's Gonna Getcha" is "quite possibly the hardest song ever made." Nas references Tim Dog on his track "Where Are They Now?" from his 2006 album Hip Hop Is Dead, and despite Tim Dog's feud with Dr. Dre, Eminem name-checked him on the track "Ricky Ticky Toc".

Penicillin on Wax is the debut studio album by American New York-based rapper Tim Dog. It was released on November 12, 1991 via Ruffhouse Records. Production was handled by several record producers, including Ced-Gee, TR Love and Moe Love from Ultramagnetic MC's, Bobby Crawford, Louis Flores, and Tim Dog himself. Fellow rapper Kool Keith made guest appearances on two tracks.