I thought it was hoisted BY, but if it’s hoisted ON I want to be correct.
You could be right...gonna check!
"...Pétard comes from the Middle French péter, to break wind, from the root pet, expulsion of intestinal gas, derived from the Latin peditus, past participle of pedere, to break wind. In modern French, a pétard is a firecracker (and it is the basis for the word for firecracker in several other European languages).
Pétardiers were deployed during sieges of castles or fortified cities. The pétard, a rather primitive and exceedingly dangerous explosive device, comprised a brass or iron bell-shaped device filled with gunpowder and affixed to a wooden base called a madrier. This was attached to a wall or gate using hooks and rings, the fuse lit and, if successful, the resulting explosive force, concentrated at the target point, would blow a hole in the obstruction, allowing assault troops to enter.
Shakespeare's phrase, "hoist with his own petard," is an idiom that means "to be harmed by one's own plan to harm someone else" or "to fall into one's own trap", implying that one could be lifted (blown) upward by one's own bomb, or in other words, be foiled by one's own plan..."
Kind of funny!