Our office is set up really strange and to get to the women's restroom you have to walk through a large dimly lit storage area and pass through a couple of doors.
I had just finished washing my hands and turned to reach for the door to leave. Suddenly the door was flung open and scared the ever loving shit out of me.
I guess my fight or flight chose fight because the next thing I know I'm wildly swinging a right hook.
I punched my boss, who was dressed as a witch for Halloween, in the jaw/neck as we screamed at each other.
We've now had two "safety meetings" about preventing future incidents,
they've made laminated signs and taped them to the bathroom door that say "Please open SLOWLY" and every woman in the office now announces themselves every time they come in or out of the office.
I got a verbal warning from HR and I'm now too afraid to use the office restroom because I don't know if I can be trusted when startled.
I sat through a meeting about it dressed as a bumble bee and trying to not laugh and cry at the same time.
Edit: I'm a female. Boss is female.
Edit Edit: Boss was also dressed like a witch for Halloween.