I still got grudges from 40 years ago. Does that count?
I got a good one for you.
I sold a guy an RF amplifier like 25? years ago , he connected it backwards (despite the warning that I passed along about the wire colors being wrong) and blew the f***ing thing up, then blamed me for it.... and because of
his "prominence" on the radio I was publicly cajoled into giving him a refund. That still pisses me off, despite the fact that the guy who did it has long since died. I still have the amp, got it rebuilt with new Motorola MRF-455s... which wasn't too bad, but what really sucked was it had MRF-454s in it, which were more powerful, but at the time, were made of unobtainium. (MaCom hadn't started making 454 clones yet).
Now that having been said, if he was actually a real friend, I would have given him the money back without even being asked, and then I would have just given him shit for the rest of his life about it (eg like "remember when you.... lol" but because he was a huge douche, I gave him his money back, got the amp back and never talked to him ever again. Like as in ever. Not even once. I don't think he was ready for that part, though.
Guy: "Do you think mike is pissed at me he won't talk to me on the radio."
My (mutual) friend: "Gee, what do you think? (laughing)"
-Mike