Slightly off topic but...
A 'Master' Key..
Any lock that will get opened by any key is just a s****y lock...
My front door lock
Do you honestly have one of those on your front door?
They run off a mortise latch, which offers about the same security as a door handle or a "Yale" type lock (nightlatch).
Saw this type of lock on mythbusters and it was easily defeated!!