Lock bumping is a lock picking technique for opening a pin tumbler lock using a specially craftedbump key. A bump key must correspond with the target lock in order to function correctly.The history of bumping locks goes back to 1970s when some locksmiths in Denmark shared a technique for knocking on a lock cylinder, in which an ordinary key can be filed so that, when it is inserted into a door lock and tapped, the internal pins can be jarred in such a way that the lock will open.