Mexican Fountain 

The act of urinating inside the vagina of a woman during sexual intercourse.

Chad and RayRay are in the middle of fucking...

Chad: "Do you want me to pee inside you?"

RayRay: "No thankyou. I'm not interested in recieving a Mexican Fountain from you. Tell your dugan to hold it."

Mexican Fountain by Dr. Humpsalot June 11, 2006

Mexican Ass Fountain 

Initial steady stream of shit disbursed through the anus ( usually accompanying sever anal burning) whilst on the toilet after a hefty meal of Mexican food.

"I was so sick after I ate five tacos at that Mexican restaurant, talk about a Mexican Ass Fountain!

Mexican Ass Fountain by James Casey & Matt Druken May 22, 2008