Or something a bit different? Examples of being hoisted by one's own petard would be appreciated.
A Petard was used during the medieval times as a way to breach a gated castle. It was a box or trough, loaded with black powder, placed on a long stick. The fuse had to be lit before the petard could be run up to the castle gate while being fired on from above. If the man placing the petard against the castle door did it correct, the door could be blown open. If the fuse went too soon, the man placing this charge would likely be hoisted into the air by the explosion and probably have the4 stick blown threw him. In other words, being hoisted on his own petard. Also could be construed as saying you were cause of your own demise.
A petard was originally the noise made by flatulence but came to mean an explosive device that one had to actually attach to whatever you wished to blow up, a sort of Elizabethan sticky bomb. If you attached it and took too long in moving far enough away after you had lit the fuse, you might be blown up yourself when it exploded, i.e. hoist (carried abruptly upward) by your own explosive device.
Your karma' is what you get as a result of being Hoisted by your own Petard..!
A petard is (or was) a small bomb. If a petard were to detonate prematurely one would be lifted or hoisted into the air, thus hoisted by ones own petard. That's really the only example I can think of.
