I fichissimi (1981)

Mechanic Romeo and grocery deliverer Felice lead two rival gangs and the local discotheque is not big enough for the both of them. When Romeo falls for Felice's sister, conveniently called Giulietta, the entire town becomes too small for the two rivals. Romeo is adamant to keep on seeing Giulietta while keeping clear of Felice, while Felice is forcing other suitors onto his sister that are more to his liking.