Hell's Angels '69

Two rich brothers want to rob a Las Vegas casino, just for the fun and thrill. They decide to use the Oakland, California Hell's Angels as dupes in their plans by pretending to be members of an East Coast motorcycle club/gang and winning the Angels' trust, and then using them to create a disturbance outside the casino while they are inside robbing it. Everything goes as planned—the brothers even manipulate the Angels into telling them to go away—but then a small mistake results in the Angels figuring out that they've been used—and nobody makes fools of the Hell's Angels.