idk how widespread this is, but here's one I was hit with recently that I needed to have explained to me: "terete", which fighting game players were saying whenever a player won with a cinematic super—turns out it's a we-say-this-so-often-we-don't-inflect-anymore derivation of "te ♪re~ ♪tte~ ♪", ie the opening "you wa shock" refrain from Fist of the North Star, which plays in instrumental form whenever you hit a Fatal KO in the Arcsys fighting game
come to think of it, here's an example of a piece of JP terminology that's matriculated to EN circles, to the amusement of some JP folk:
many long-standing Tetris mechanics are commonly referenced via three-letter acronyms: DAS (delayed auto-shift, ie the specifics of how pieces move when the left/right input is held), ARS and SRS (Arika Rotation System/Super Rotation System: different rulesets for how pieces rotate and kick, etc).
One such term is ARE, used to refer to the forced duration between a piece locking and a new piece spawning... but it doesn't stand for anything, it's literally just the JP word "あれ (ah-ray)" written as if it's an initialism, and it's not a word like "abare" that succinctly describes a very specific concept, it's basically just a filler word (akin to "that thing") that people would use offhandedly without explicitly defining what they're talking about, so it's kinda silly that it's jumped the language barrier and not been substituted for something that's at least a little bit descriptive.
a certain TGS panel just gave me the backstory to a certain piece of jargon that I'd occasionally heard/read but never understood out of context: "Tamaki (玉置)", a slang term for safe spots, ie specific areas on the screen where the player will be unable to be hit by enemies/bosses/attacks—it's a reference to the lead singer of the early-'80s rock band Anzen Chitai ("Safety Zone"), and the term was specifically concocted by the magazine Gamest in order to keep publishing strategy info without drawing the attention of certain arcade game makers who didn't want info like safe spots being proliferated, as they saw them as tantamount to bugs and harmful to a game's income. I think I'd just presumed it was the name of some old Xevious player or somethin'.
(Apparently Toaplan was one of the few big arcade devs of the day who approved and actively welcomed articles on strategies like safe spots.)
