We interrupt this regularly scheduled bathroom break

Question for you: Do you talk to people while they are using the bathroom? I'm not talking about family members, I mean coworkers.

Yesterday I went to the bathroom and bosslady was at the sink. Of course I spoke and then went into the stall, but she kept talking. Talking about her vacation, where she went last year, how she wasn't going to have time to go this year, blahblahblah. The whole time I'm thinking, I am trying to pee! I couldn't do it. I was so uncomfortable with her talking to me while my pants were down that I couldn't even use the bathroom. So I walked out and continued our conversation and went back to my office. I was telling my sister about it and was like that was rude, you don't talk to somebody while they are peeing. And my sister asked "says who?" I stopped and thought about it, I just thought it was one of those unspoken rules or common courtesy, but apparently not. My sister was like don't be mad at her because you can't perform with an audience! So that brings me to my question again. Do you talk to people while they are using the bathroom? Do you find it uncomfortable when people do?