I got reprimanded once for threatening a customer while working at radioshack. It was after work, and I was off the clock, but I did it right in front of the store and was still wearing my shitshack shirt. Guy started acting like a dick to one of my coworkers, so I took over the sale for her, and he starts getting loud with me, to which I stay subtle and ask him to calm down, he's swearing in front of children and disrupting other customers. His friend says I can go fuck myself and they both walk outside. My shift had been done for a few minutes already so I clocked out and walked outside, and sure enough both of them were standing there. So I said (quoted by the way)
"If you ever come inside this store again with that kind of attitude, I will fucking throw you through the window and beat you so bloody that my curb will need a new layer of cement to cover your brainsplatter. Get the fuck away from here right now and NEVER come back, cuz if you do, I'll find out."
So a week later my boss pulls me aside and says "hey (Agent D.) did you threaten a customer last week?". I said no, I threatened a jerkoff outside of the store who had been in there earlier, but I wasn't working at the time. My boss chuckled, but said he had to write me up for poor conduct. I should point out I had a ton of write ups for being a poor salesmen, so I didn't give a shit anyway. I asked if he would have handled it differently, though. He said he couodn't answer that, so I said fine.
Funny story, he did come back, saw me, and booked it as soon as I looked at him.
Quick edit: Yeah the whole point was fuck the stupid rules, you look out for those who can't defend themselves.