Queensbridge, N.Y. hip-hop duo Mobb Deep has a history of pushing boundaries. Originally formed in 1992, their early recordings—Hell on Earth and The Infamous—pushed the limits of socially acceptable violent and sexually explicit lyrics, but these albums set the stage for two decades of collaboration and experimentation. None of their creative output has reached the critically and commercially successful standard set by their breakout work, but experimentation is vital for all artists, even Havoc and Prodigy. Experience the legendary hip-hop act at a 21-and-over show on Friday, April 19 at Sister (407 Central NW). Philadelphia-based producer, emcee and singer-songwriter Hezekiah and DJ Dozer kick things off starting at 9 p.m., and presale tickets are $40.