If you don't know what a doobie is, then brother, chances are you weren't around when the Doobie Brothers lit up the Top 40 charts while scoring big back in the '70s. In retrospect, that multiplatinum success seems somewhat ironic for a group that borrowed its handle from a slang term for marijuana and subsequently kicked off its career as a Northern California biker band. Face it — dopers who hang with the Hell's Angels aren't always embraced by the masses. Regardless, the band's hit singles —"Listen to the Music," "China Grove," "Long Train Runnin', " and "Black Water" — and megaselling albums — Toulouse Street, The Captain and Me, and What Were Once Vices Are Now Habits — kept these Doobies smoking. The recruitment of former Steely Dan sideman Michael McDonald may have mellowed out their music, but his mush-mouthed vocals on Takin' It to the Streets, Livin' on the Fault Line, and Minute by Minute made the later Doobies more potent than ever. McDonald would eventually create his own buzz, but the band soldiered on without him, through bummers, breakups, and comebacks. The current lineup includes linchpins Patrick Simmons, Tom Johnston, Michael Hossack, and John McFee, and, as evidenced by their last Hard Rock appearance, today's Doobies remain as fired up as ever.