Loiding is the use of a flat object such as a credit card to shim spring-latch locks on doors. It is a form of bypass. The flat object is slid between the latch and strike plate and used to retract the latch.
Modern spring-latch doors use a deadlatch or dead locking plunger to prevent loiding.
Loiding can be considered a form of surreptitious entry as it leaves behind no evidence of its use if done correctly.