jiggler

Someone or something that jiggles.

A key, now especially a car key, that has been partially ground down so that it will open many locks.

This may be accomplished by means of jiggler keys used for opening door locks. Such keys are of two types: those for opening locks having two sets of tumblers, and those for opening locks having only one set.

I knew about the whole key “jigglers.” Basically, random car keys are shaved down with a file, rounding out sharp edges.