look up any word, like bukkake:
 
1.
When you diarrhea or just poo on a girls lower back, and you wash it down her buttcrack with piss and it rushes down the back like the rio grande river.
Rick -Did i i see you pullin the ol' rio grande on chelsea last night??

Dave - YEP!
by shortbuthard October 26, 2009
 
2.
Adjective:

Very much like the Rio Grande is on the border of Texas and Mexico, a man who is described as being Rio Grande is on the border of being gay. Used for metrosexual or just questionable guys, usually ones into musicals or that are very stylish.
Girl to friend:"(Insert guy's name) is totally hot and we get along great but he's kind of Rio Grande, I'm not sure if he wants to take me home or that guy over there."

or

Guy to Friend:"I made a killing at the J.Crew summer sale and then watched 'Rent' for like like billionth time yesterday, it was awesome."
Friend:"Dude, you are so Rio Grande."
by UDallday April 25, 2009
 
3.
The act of urinating in your partners asshole, thus increasing the satisfaction of orgasm.
Yo phil i rio grande'd in your moms ass last night.
by G-Money 22 June 02, 2006
 
4.
Espanol for "Great River"

One of several rivers where the gringoes dump their shit into before reaching Mexico. All rivers that are shared by the Yanks and Mexicans flow from the EUA south into Mexico. In the case of the Colorado River, the Californians, Nevadans, and Arizonans pretty much take everything of value out of it before it flows south of the border.
Every year, thousands of illegal migrant workers wade across the Rio Grande and back for starving wages and the constant threat of being poisoned by pestacides and other leathal substances. They're the reason the Yanks can get such cheap meat and produce at the local supermarket.
by Miskatonic Jack 2 December 09, 2006