Mistress Julia and mistress Rosella are mature mistresses who love to have fun with young guys. But this young guy did not know how to please them and he was clueless. He had to be punished and the mistresses used their pee to do it. They thought that pee was softer and a way to send a message to that if he did not change and become as naughty as they wanted, he would get a worse punishment.
This mistress hates liars and this guy was one. She was not going to condone any of the nonsense he did and that is why she felt that the best way to send a message to him was to turn him into a human toilet. So she stripped him naked and did the same to herself and that is how she made him drink her pee. The humiliation was instant and he learned his lesson.