A booby trap is a device set up to be triggered by an unsuspecting victim. As the word trap implies, they often have some form of bait designed to lure the victim towards it. However, in other cases the device is triggered when the victim performs some type of everyday action e.g. opening a door, picking something up or switching something on. Lethal booby traps are often used in warfare, particularly guerilla warfare, and traps designed to cause injury or pain are also sometimes used by criminals wanting to protect drugs or other illicit property, and by some owners of legal property who wish to protect it from theft. Booby traps which merely cause discomfort or embarrassment are a popular form of practical joke.
Trap used by Vietnamese, at Cu Chi Tunnels.