Simply put, urinating inside her rectum will result in an enema-like reaction. Found out the hard way. Also both parties need to disclose any prescription medications they’re using because said medications are excreted in the urine in measurable levels that can adversely affect the person who’s being urinated into.
Could you tell us more about that experience in particular and about pissing in the rectum in general? You seem to have plenty of interesting insight in BBW related topics