At the clinic where I work we have the typical phone intercomm system but the rings are very similar. One day it was a bit slow and we were screwing around crank calling each other around the office. My phone rang at the precise moment the intercomm did so I just grabbed it and shouted "What the F*&$% do you want now"? It was a patient calling in and not the intercomm of one of the screwballs that I work with. She said "I think I got the wrong number" and then hung up. I felt a wee bit sheepish over that little manuever.
When it comes to gender confusion back when I worked as an EMT one of my partners was a very male looking gal. We had a call for a possible stroke at the YMCA in the shower room. It was a senior citizen day and we were in the shower room getting vitals and history from the patient. Then little old men started comming in and hopping in the shower oblivious of my partner who they must of assumed was a guy. They did not have thier glasses either which only compounded the situation. She went beet red within seconds and was rapidly losing her composure. I was doing everything to keep from busting my gut laughing. After we loaded the guy up and were on the way to the hosp. she came up to the front of the ambulance and informed me if I told anyone about this I would be nuetered.
I would bring back that hideous memory for her at strategic times for years after that.