One of my favorites happened during my first post-college job. I was working in an infectious diseases lab for this MD/PhD who was every bit the mad scientist - brilliant as hell, but no social skills whatsoever. He just couldn't deal with people at all. I should have been wary when, during my first week, I had the department head (with whom my boss had clashed on many occasions) say to me "If he gives you a hard time, you just let me know. I'll deal with him."
So the one day, I made a mistake. I forgot to carry a one, or my decimal place was off in my calculation, or something. I don't remember. But I ended up using a lot more of a particular enzyme than I should have used. (By "a lot" I mean a microliter instead of a picometer, but enough to blow the entire experiment to hell and back) It was my mistake, and I owned up to it. I was completely willing to be chastised, and I sat there for a while listening to him berate me. But he just WOULD. NOT. STOP. Finally I stopped him in mid-sentence and said "John, enough. If you'd stop yelling for a minute, I'd have the time to go build the time machine that you're obviously expecting me to create, so I can go back and change the past. Now, if you'll excuse me, I have a space-time continuum to contend with." It was awesome, because he started laughing and I started laughing and our relationship improved SO much from just that one exchange. In fact, the best work references I've ever received have come from him.