Producer: Earthtone III

OutKast was no stranger to creating unconventional music--witness "Synthesizer" on Aquemini and "E.T." on ATLiens--but when they came out spitting fire over some sort of futuro-electro-d&b chaos, all bets were officially off. The fact that 3000 sounded like he'd been born to rap like that? Fuck what you heard, they just fucked everything you'd heard.

"B.O.B." clocks in at 155 beats per minute—the exact same tempo as Keri Hilson's "Knock You Down." Who woulda thunk?