hype man
n.— «Hype-men, for those of you unfamiliar with the lingo, are the fellas you see at rap shows who stand next to MCs and bellow certain words along with the rap to add emphasis.» —“I Love a Parade: Radar Station hitches a ride with great big rappers” by Jordan Harper Riverfront Times (St. Louis, Mo.) May 26, 2004. (source: Double-Tongued Dictionary)