Just for the Hell of It(1968)

A teenage gang led by the vicious Dexter, with his girlfriend Bitsy and friends Denny and Lummox, creates havoc in a small Florida town by harassing various people and vandalizing property... just for the hell of it. When a former gang member, Doug, tries to prevent their ever increasing violent antics, Denny takes it upon himself and a few loyal members of the gang to target Doug's girlfriend, Jeanne, to make him back off.