I'm trying to identify a featurette that accompanied Raiders of the Lost Ark at the movies, so I guess I'd have seen it in 1981.
From memory, the featurette was set in a British public boarding school. A group of entrepreneurial students clean up by selling their classmates insurance policies that pay out if they get a beating. The headmaster gets wind of the scheme and tries to thwart the cocky little upstarts by giving the cane to every boy who bought insurance. Unable to pay on all the policies at once, and facing the wrath of their insurees, the gang solves the problem in some way I can't recall. However, it involved the discovery of an arcane law or legal precedent allowing them to throw themselves a lavish party and literally consume their expenses.