One time my coach was throwing BP but he had coffee in one hand and not a glove. I was up and they were pretty good height pitches since I'm short and normally the pitches were too high for me during BP back then. But he threw one that I lined back at him and nailed him in the side and he dropped his coffee all over the mound. Pretty nasty stuff to have all over a mound, but to top it off he landed in the coffee since he dropped like a sack of bricks. He's was a bit older and I guess couldn't take much of a hit.
EDIT: Oh, and he couldn't really get up either, the assistant coach had to help him get to the bench and then he had to finish BP with us. (Next pitch almost hit the assistant coach so they made me stop taking BP that day )