Radio rap is pop imitating hip-hop. It usually has a familiar, repetitive beat that uses the same sounds as the last song in a different arrangement. Subject matter typically consists of ass, booty, but cheeks, rims, jewelry, and booty. Not every rap song heard on radio is "radio rap", and an otherwise respectable rapper may release a "radio rap" track.
Shake dat ass, shake dat ass. Crunk juice, whaaat? Okaaay! 20 inch rims yeeeaaah! Look at my chain, look at my grill, et cetera, okaaay! -Radio Rap