I've been a PAX when someone got V. obnoxious with the cabin crew [he wasn't pi**ed, just one of life's a**holes]. After he was served lunch he started to complain loudly about everything. He took great delight in belittleing one particular girl [aged about 25] who was clearly gritting her teeth and kept smiling and being pleasant. This got him even more determined to break this girl's spirit. To my shame, I did nothing at the time.
Eventually, a guy got out of his seat, gently eased the girl down the isle a little and leant over the man. I couldn't hear what he said, but the a**shole didn't utter a squeak for the rest of the trip. As we got off, I handed my card to the girl and told her to contact me if there was any trouble from the 'pratt'. She smiled sweetly and told me that there was one on every flight.
Anyway, I got a call from the cabin crew personnel manager and we had a long conversation about the flight. I backed up the girl 100%. He then told me that the PAX next to Mr Obnoxious had told him that the 'Gent' who quietened down the man had threatened to 'rip his head off'. The pillock lodged an official complaint, which the personnel manager was investigating.
The pratt was subsequently banned from flying with B*, and, I believe, half a dozen other airlines [MAFIA rules, OK!].