When two or more individuals partake in sexual intercourse with a female. This reference is usually always used to mean such an act, but also can refer to taking a non-stop shit within a toilet, or any other activity that involves a certain degree of persistent that it becomes evident that it takes as long as a train to get the job accomplished.
I was running a train last night on my girlfriend.

"Was Aaron just in the bathroom running a train?"
by Josh FTW December 1, 2007
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run the train means for a group of five or more guys to line up to take turns fucking another dude in his asshole or mouth.
They wanted to run the train on me this morning in the cadet showers, so I let them -- took care of all their morning wood!
by USAF Cadet July 21, 2021
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To attend a club with your ...err...posse, pick out a bitch, and proceed to stitch train tracks onto her dress.
Jenny: Oh my god David, lets go run the train on that bitch.

David: yeah okay, got your sewing kit?
by MrTrains December 16, 2008
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Running a train when y’all both on track to get some cooche
John John the Don “ shit I thought we was running a train
by Shamiirian December 4, 2019
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When two guys have sex with one girl. One guy gives it too her in the ass and the other guy gives it to her in the pussy.
Me and my friend are gonna run the train on that chick over there with the big ass titties.
by Pavelski8 July 31, 2008
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