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Trainbow. A bunch a homosexuals runnin a train on each other. Most likely anal. Definitely butt stuff.
Hey guys, it's Bruno Mars! I bet he would love a to be on the rails when this trainbow comes steaming through his back yard.

Mitch wants to do buttstuff, so Mitch volunteered to be the caboose when his buddies invited him over for a good ol Trainbow.
by Kenternet January 18, 2017
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The train that rides the rainbow, allowing to move at light speed but at the same time bring joy to the hearts of all children.
"Whoa, did you see that Trainbow?"

"Yeah it totally just targeted some starving third world country children!"
by Redaj February 03, 2009
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