When a domme wants you to drink her piss, think of it has her asking you to drink in her very energy and essence. The water in the urine has passed through her is it carries with it her energy. When you drink the urine, the energy of the domme is carried with it into you. Her energy becomes part of you.
When you drink the piss of another person, their energy becomes you. If you are wanting to submit to that person, then their energy and “will” will infuse you from the inside and help you obey them fully. Their intentions and wants infuse you from the inside out. You are 80% water and now part of that 80% is directly from your domme.
Drinking urine is also totally safe and sterile — urine doesn’t typically contain any harmful bacteria or anything at all that will make you sick (unlike feces which is teeming with bacteria and will certainly make you sick!) Special forces are trained to drink their own urine and according to the SAS Survival Guide, you can drink your own urine up to 7 times before it is a problem from too many waste products built up in the urine. So drinking fresh urine from a domme is not going to be a problem at all.
To make drinking pee easier, make sure the domme drinks a bunch of water beforehand so the pee is diluted — and you will find that it tastes mostly like water with perhaps a little pleasant sweetness to it.
So if your Dom or Domme wants you to drink their urine, go for it! Know that it is safe to do so, a wonderful act of submission, and it will infuse you with their energy so that you are a better playtoy for them!