subs. phr. (schoolboys’).—An arrangement of books, wet sponges, vessels of water, etc., arranged on the top of a door set ajar: when the victim enters the room, the whole falls upon him.
1850. F. E. SMEDLEY, Frank Fairlegh, iii., 28. He had devoted it to the construction of what he called a BOOBY-TRAP.… The victim’s room-door was placed ajar, and upon the top thereof a Greek Lexicon, or any other equally ponderous volume, was carefully balanced, and upon this was set in its turn a jug of water. If all these were properly adjusted, the catastrophe above described was certain to ensue when the door was opened.
1882. T. A. GUTHRIE (‘F. Anstey’), Vice Versâ, xiv. ‘I made a first-rate BOOBY-TRAP, though, one day for an old yellow buffer who came in to see you.’
1883. The Saturday Review, 3 Nov., 566, 2. He is suddenly drenched from head to foot by a BOOBY-TRAP—a sponge soaked in water placed above a half-open door.
