 French rap is filled with slang that is hard for even French-speakers to understand; whole songs are delivered in Verlan, the ingenious, dizzying slang in which words are reversed or recombined.Like France's chanson tradition, French rap is also famous for emphasizing lyrics, and the rappers are widely viewed as heirs to the chansonniers.In the late 1990s, Lino and Calbo teamed up with a group of rappers who were also second-generation Africans, on a collaborative project called Bisso Na Bisso, an expression which means "just between ourselves" in Lingala, the most commonly spoken language in the Congo region.