I'm trying to make her understand that even age is irrelevant in my point: even a perfectly healthy 20-something-year-old can't hold it forever, and will eventually wet/soil themselves. You can't will your body to have unlimited storage space. That's physically impossible.

LOL, I don't think I "won" anything. Here I have a friend with fantasy expectations of the human body. God forbid she ever finds herself in a situation where she can't get to a toilet for, I dunno, a whole weekend (which has happened to me before). I think it's really sad when people shame themselves for having universal human vulnerabilities. It doesn't mean you're sick, or a failure.

Anyway, sorry if this is all silly. I just feel like the laws of physics are seriously being slandered here. And Google provides no answers. So I came here.