I cannot believe that she said it, having had two children. She seems to be extremely controlling in a really weird, grotesque way.

The rule of hygiene for women is to void the bladder as soon as possible to avoid urinary tract infections. I have no idea about men, but as was pointed out above by SnakeCharmer, extreme patience led one man to his grave...

If this conversation ever returns, ask her how long she'd be willing to not drink any liquids. Because if she believes that a healthy human has full control of the outflow of liquid, she should be able to demonstrate equally limitless control of the inflow.