medieval french guy inventing the petard: I’ve invented an ow do you say, exploseev. I shall name it after a fart and a zousand years from now no one will know what eet is except in ze context of backfiring spectacularly
the word "hoist" was originally the past tense of another word "hoise", and the phrase "hoist by my own petard" is grammatically in past tense. partially thanks to the popularity of that phrase, "hoise" fell out of fashion and "hoist" is now the present tense with "hoisted" as the new made up past tense form