Comment by pineaux

Former locksmith here. That is called "to flipper" a door. (Guess that is where the flipperzero name comes from)

However you can only flipper doors that are held closed by the latch bolt. If the lock deadbolt is engaged, you cannot flipper it, because the deadbolt will not budge when manipulated by a card or piece of plastic.

Technically a lock without an engaged deadbolt is not really "locked" but "closed". That being said, an unbelievable amount of people believe their doors are locked when in fact they are closed.