jimmy (ENG. US)
NOUN (plural jimmies)
A short crowbar used by a burglar to force open a window or door.

VERB (jimmies, jimmying, jimmied)
[with object] informal
Force open (a window or door) with a jimmy.

The British English term for the housebreaker’s implement was usually jemmy, still common here and also in Australia and New Zealand. Authorities are fairly sure that this word — and the verb to jemmy or to jimmy derived from it — did come from a familiar form of James, though precisely why seems likely to remain for ever a mystery. There seems to be a strong tradition of giving tools the names of people. Another thieves’ term for a short iron bar used to force locks or break open doors was bess; yet another was billy. Think of the jack you use to lift the car when you’re replacing a wheel — this seems to be from the familiar form of John. Yet another example is the term derrick for a type of crane, named after a famous early seventeenth-century hangman.