jehu (JAY-hoo) — noun: a cabbie, or a reckless driverYes, I realize those two definitions could be considered synonymous. I think that's the point. Almost doubtlessly a term that's been around a while, judging from the fact that it comes to us from the Bible. Jehu, for you Old Testament illiterate, was one of the kings of Israel, and a military leader known for his chariot attacks, hence his transformation into a common noun. Notably, Jehu's backstory seems to be populated by other people with "J" names that have made their way into common parlance. For starters, he's the son of Jehosaphat — who, to my knowledge, wasn't known for jumping — and he's also the one responsible for ordering that slutty, smutty Jezebel to be thrown out the window, whereupon dogs ate her. (A favorite childhood story, that one.) And if "jezebel" isn't a familiar modern term for you, then you must keep especially good company.
A random note on Jezebel, while I'm on the subject: Wikipedia claims that Jezebel was the aunt of Dido, who, in my opinion, is one of the more interesting mythological ladies and another member of ancient royalty who met a fairly bad end.