A sticky-sweet summer confection if ever there was one, this highlight from Gym Class Heroes frontman Travie McCoy finds him teaming up with Gnarls Barkley's Cee-Lo Green and dishing out whipcrack, mile-a-minute raps between Lo's high-gliding, R&B vocal hook. "Dr. Feelgood" is a brisk, funky number, punctuated by tight guitar stabs and bright blasts of organ. Considering McCoy's addiction to painkillers, which he's since kicked, it's a bit odd to hear him rapping, "She's got a set of lips like a sedative/and every time I kiss, it's like medicine." Who's the femme fatale who could inspire that conflicted analogy?

“Tonight's the Night”

The lead cut and title track from this girl group's debut album, "Tonight's the Night" was written by 19-year-old bandmember Shirley Owens, who sings lead, and producer Luther Dixon. The band from Passaic, New Jersey met in high school, first calling themselves the Pequellos. The song's frank thoughts about sexual and emotional surrender was racy for the time, but that didn't stop the Chiffons from cutting a similar version immediately after the original came out. "We were the first female group to write some of our own material," band member Beverly Lee recalls. "We did have some say-so in our writing."