I have had to do it several times in front of nurses. Once I had an insurance exam and it said right on the form that the examiner had to witness the urine production. That time the nurse doing the exam was very cute, I was in my late 20s, and afraid of getting an erection. I was standing there in front of her wearing just an undershirt, everything else was off, and that was about to come off...and...I couldn't pee. We were standing in a little toilet room off the exam room, she was staring intently at my penis, I was trying to pee and NOT get an erection. So she turned on the faucet of the sink, and we waited. After a full minute or two I was able to pee. She watched the entire thing. After that she went on with the exam and, you guessed it, I got an erection. And kept it for the rest of the exam. To my surprise she was not in the least displeased that I did, in fact I think she liked it. Really. This is a true story by the way, not some sort of fantasy. It was the first of what turned out to be many exams and procedures with female doctors and nurses during which I got an erection, and came to realize they actually seemed to like or even prefer my doing so. I mean it was not that I was a threat to them at all, or acted menacingly, or came on to them. Just the opposite really. And back then, I was very shy about it and having an erection like that was embarrassing. (I probably act similarly even today, because it is an odd situation. I have had a few nurses or doctors put me at my ease when it happens, saying it is natural, etc.) But having to pee in front of that nurse the first time was, oddly, even more embarrassing for me then. Go figure. Best I can come up with is this: I have had erections with various women during my life that I was about to have sex with. Hundreds of times. So in that sense it is "natural" to have an erection in front of a woman. But I do not pee in front of them, except during urine collections such as described here. By the way, this may, or may not, also explain why it seems that so many medical women seem not in the least offended by seeing a male patient with an erection. Or even prefer it. It is because in their private lives if they see adult males nude at all it will likely be with an erection, because they are about to have sex with that man. So, by the same token, it is "natural" for them.