Bumping” a lock vs. picking a lock. -- Bumping, also referred to as “rapping” is not a new technique for opening locked car doors. In fact, it’s been around for at least half a century! When this method is used correctly it is extremely effective in over 90% cylinder type locks. As with any other lock picking technique it requires some time and patience to be able to master. A bump key is a key in which all the cuts are at the maximum depth (999). Bump keys can be cut for standard pin tumbler type locks as well as “dimple” locks.