What may work even better than a can is a metal clothes hanger that has been flattened with a hammer. Make it just flat enough so it can fit into the lock and only flatten half an inch (2.5cm) of the tip. First pull down on the lock and put the shim in on the right side of the shackle on the inside. Then push the lock up while jiggling the shim and push down again on the lock. Repeat pulling the lock down and up with pressure on the shim until the lock pops open.