When a train captain drives a train into a woman's vagina.
Man 1: Did you fuck her?

Man 2: Yea, but she was loose enough to give an underground railroad.
by Skeetman69 December 6, 2008
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When 2 black guys are running train on a girl.
1.) "Yo Jared, did you hear that Stephanie was riding the underground railroad last night?"

2.) Luis and Tivo gave Monica a ride on the underground railroad last night.
by theMASShole March 27, 2012
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A legion of anal driven women using horse cock size strap-ons as means of their sexual intercourse, form a circle of consecutive anal penetration. It is at this point that each member donkey punches the participant in front of them forcing defication. Said feces is then tossed gently and accurately into the center of the circle where a concetric circle of outward facing males who are in fact beating off vigorously, racing each other for their nut. The loser's punishment is to crawl through a tunnel made by the legs of the participants while they each take turns shitting on him. *note that the loser has to crawl slowly and with their back to the floor, and mouth open wide.*
-"Hey, since we have nothing else to do today 20 horse cock strap-ons, wanna take a ride on the secret The Underground Railroad today?"
-"Yeah man, that sounds great, just don't let any weirdos in this time!"
by Charlie Octopus September 20, 2013
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Two or more black males having sex with a black female, whilst in a basement.
Black_Guy1: Yo, me & Chanel had an Underground RailRoad last night!

Black_Guy2: Tight, dawg!
by NitroFight53 August 22, 2010
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The act of scissoring assholes and transferring shit from one anus to the other
Guy 1: "What did you two do last night?"
Guy 2: "We were underground railroading until our asses overflowed!"
by thechocolatestarfish April 28, 2014
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when a girl starts sucking on your balls, then licks your gooch, and finishes it off with a rimjob. It's a funny experience that feels great, but is secretive just like the real underground railroad from back in the day.
So last night this slam piece was sucking my dick when all of the sudden she gave me the underground railroad
by rocklobster 69 October 4, 2011
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The toilet and/or the entire human fecal system.

Called the underground railroad because "black shit escapes."
Goddamnit, I better go visit the underground railroad.
by sal May 18, 2004
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