In high school I worked at a car wash. While I was wiping rail dust out of a guy's rims he swung the door open and hit me square on the top of the head and dropped me like a stone. He then proceeded to berate me for being stupid and slow for not getting the soap film off of his rocker panels. (That I couldn't see because I was A: on the other side of the door, and B: Trying to regain my senses). I stood up and handed my towels to the floor manager, said "ask me when you're done with him" and I walked out the back of the garage.
Fast forward 6 years. I am bartending at a local family establishment and the same asshole comes in with his wife. From the first minute he's bitching about stuff. I'm pleasant, but brief with them. Eventually they decide they'd like to eat in the bar and ask for menus. I get them their menus and after serving a few more patrons, I walk over with a pad and pen and ask to take their order. Douchebag says "You're gonna take our order? I thought I'd get one of these hot blonde waitresses." His wife was visibly uncomfortable so I shot back and said "your wife called ahead and asked for a young stud bartender". After their meal she slid me five bucks under her plate while he was bitching about the food.
About a month later in the same restaurant, he totally unloaded on a waitress for no reason. I was bartending and I kicked him out. He lost his mind, screaming about how he knew the owner his whole life and how I was done working there. I pulled out the owner's business card, handed it to him and said "Bob gets in at 9:00, that's his number".
11:00 the next morning the owner called me and said "I heard you kicked out Tyson last night". I said "yes I did", and proceeded to explain the scenario. He paused for a few seconds and said..."you did the right thing, he's an asshole. When you are on that side of my bar it's your bar, ad they're your staff. Keep it up."