My wife does not share my kink, and is generally reluctant to discuss pee-related topics with me.
So in the past, I've occasionally tried to casually bring things up in discussion with my female friends... to hear their stories, pick their brains, etc. I obviously have to be careful - I don't want to creep them out, so I try to bring the topic up casually.
I have a few close female friends that I'm comfortable talking to like this, especially my friend "K", who I've discussed here in t