Sonic screwdriver

A (fictional) device possessed by Dr Who which is capable of extricating the doctor from difficult situations. It operates on virtually any lock enabling him to escape, and is a useful tool for many other tasks besides. The details of the sonic screwdriver's abilities vary somewhat from episode to episode, and are never explicitly explained, but it is thought that it operates through the use of sound waves to exert physical forces on objects remotely (such as the mechanism inside locks).