She will drink all the piss

"Open wide, young lady", ordered your mother. There was your sister, kneeling, still looking defiant but determined to be your urinal, with her mouth open as your mother said. Without further delayed the pee flowed into his sweet mouth.

Immediately the urine gathered in his open mouth was showing you a vision of your sister that you had never seen before. You felt the color contrast of her red lips around the yellow urine excites you very much.

And now was the time for her to do what an urinal must do.

"Swallow it," your mother ordered. Then Andrea closed her mouth, closed her eyes, and with disgusted face she tried to swallow everything, but she had an arcade and she spilled some pee.

"Control yourself! This way you will not be able to excite your brother being his urinal!"

"I can not help it, it's disgusting piss," replied your sister as she coughed, still ashamed and humiliated.

"Relax and let the urine flow inside you, with his dick inside your mouth you must drink at the same speed that your brother is pissing"

It is disconcerting to see your mother giving advice to your sister on how to drink urine, as if she were an expert on this. "Mama, how do you know so much about watersports?", you asked. "Oh, it was thanks to your late father, he loved to use me as an urinal." Such a revelation, you feel that from now on you will no longer look at your mother in the same way.

"Come on, honey, I'll help you." Then your mother brought your sister's mouth to your cock and when you felt that you had the tip inside her you continue pissing, slowly, so your sister could swallow it. Both ,brother pissing and sister drinking, synchronized.

Glub, glub, glub. It was so exciting to hear your sister being an urinal, and so when you finish your member was already hard and ready for action.

"That's my girl, mommy is proud of you", was the only thing your mother said at the end, smiling and happy to see his daughter being her brother's urinal.

"Okay, I've been your urinal, happy? Oh, my god, this have excite you very much!" Said your sister Andrea surprised but with a hint of excitement to see your cock harder than ever.