For being 3 minutes late back from my lunchbreak. When I was about 40, I had a new office manager (she was 23,) who she was trying to make her mark, and charged up to me as I walked through the door, 3 minutes late from lunch, and said (hand on hip, head tilted,) 'WHERE have you been?!' her face purple with rage. I said 'errr, to lunch.' She said 'you are five minutes LATE!' 😡 I said '3 actually, and it's because I got stuck at a checkout a bit longer than I would have liked. I'm sorry... ' She went on.... 'I am not having it, there is literally NO excuse for bad timekeeping, you will be on a warning if this ever happens AGAIN!' 
I actually laughed, and said 'dude, it's 3 minutes!' 😆The other 5 colleagues in the office were struggling to not piss themselves laughing, this little madam throwing her weight around like a big boss. I said 'I have worked half an hour to 45 minutes past my finish time, as a favour to the company, 4 times in the past 2 weeks, with no extra pay, as I am salaried. In fact, I have always done this quite regularly, does 3 minutes really matter that much?'
She continued ranting, and almost had steam coming out of her nose! 'NOOOOOOOO excuses, I'm not having it!'
I was like 'OK then. I will work 3 minutes after my finish time tonight to make up for the 'lost time.' (I had literally lost another 5 minutes because of her having a go at me and ranting at me - in front of everyone else! Like fuck was I making that up though!)
Never EVER worked any extra time again, not a fucking microsecond. A number of times she begged me to stay an extra 20 to 30 minutes or so, so this or that certain task could be finished,' and I said 'no.' and walked off, every time.
She knew she had burnt her bridges. And the area manager was furious when he found out why I was refusing to stay over ever again. She never apologised though, so I never worked over again. Until she left 15 months later.