I had a huge fight with my girlfriend about eight years ago (and eventually broke up) because I insisted that everyone has peed in the shower at some point in their life.
She went eewwww!, and insisted that she never, ever peed in the shower or bath, even as a kid.
At the time, we were laughing it up at a party and having a few brews and one by one, everyone admitted (even the girls) that yes, they too had peed in the shower, even if only once.
But my girlfriend, as the night went on, got madder and madder when some people kept insisting that everyone has peed in the shower, and those who deny it are just lying.
To make a long story short, she got really ticked off at me for bringing up the subject, and we ended up breaking up about a week later.
I guess your girlfriend got pissed off (which is better than getting pissed on)
Yeah, probably not something to tell the g/f about. I can see how that could end a relationship. She probably could never look at you the same after that.
I'm with your ex-gf. Maybe by everyone, your pals were including little kids. Some of us above the age of 3 or 4 have never peed in the shower (little children aside), have never considered it an option, aren't about to, and are telling the truth.
Perhaps some of the supposed shower pee-ers are stretching the truth.