Most 19th and 20th century gallows featured a trapdoor, usually with two flaps. The victim was placed at the join.The edge of a trapdoor farthest from the hinge accelerates faster than gravity, so that the victim does not hit the flaps but falls freely
The word "trapdoor" or simply "trappies" can be used as an expression of dismay or defeat, in an acknowledgment that something has not gone to plan, or that someone has committed a schoolboy error of some kind, eg. leaving English to go and play mini-soccer. It is generally accompanied by a hand gesture and an exclamation of "trappies" in a sneering and obnoxious surf-voice.