I think we could have a whole thread to talk about how people misheard Ryu‘s hadōken in Street Fighter II! I worked with a person once who swore it was ’gadooka'.
A friend of mine and I used to joke that Cyclops's gene splice sounded like 'jesus christ'. I still think it sounds a little like that! But I think it was mostly just playing on arcade cabinets with shitty or busted speakers.
Not quite a fighting game but my family and I used to think that Axel shouted “Grab the power!” when he did his Grand Upper move, and we interpreted Blaze as saying “It's your daughter!”
I forget which game it’s in, but there’s a great voice sample where Guile sounds like he’s from Baltimore and I love it (something like ‘sawnic BEWWWM’)