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2.
When guys are having sex with girls on bunk beds, when one guy gets tired of humping, the other takes over and his humping motion rocks the bunk beds so the other guy can keep it going with his girl while regaining his stamina.
guy 1: "Yo bro bunk bed sex is the best cuz when i get tired, you can fuck your girl and rock the beds for me so i can take a break while still getting off."
guy 2: "What!?!?"
guy 3: "Yea man you gotta ride the train at least once in your life"
guy 1: "thank you!!! thats what im talking about!!"
by Senior Suave September 27, 2009
 
1.
to have sex with multiple people at once
Yo, me and my bros wanna ride the train with u and ur friends tonight, u down?
by clueless human January 28, 2009