I found out recently that my sub/gf has a piss fetish. She wants me to control when she pees and where she pees. The first night that we decided to try this out, I made her drink water all evening, while teasing her as well. I told her that she was only allowed to wear her panties, and nothing else. After a few hours of teasing and drinking water, she started to feel the urge to pee. She begged to be allowed to pee and finally, after a lot of begging, I told her yes... But I told her that she couldn't pee in the toilet, and she couldn't take off her panties. I told her to step in to the bathtu