Are they BOPPER minis from Metagaming's ancient Rivets boardgame? I know there were figures made for it, although I've never seen them. At the very least they're an homage to the game. No other excuse for the can opener on the Jack Bopper, the middle two are probably Rocket Boppers, and the one on the left is a Tiny (pronounced "teeny" of course) Bopper.