Well I'm going off my basic context clues here and I doubt that its about anal intercourse like the other idiot on here said about railroaded. But I think that it means that your funneling in as in they're ignoring everything else and just sending them right there. Can be used by gamers or cops or who ever.
Look down for some horrible examples.
1. Dude 1: You see that nerd frag that whole team. Damn!
Dude 2: Yea man, he railroaded they're ass.
2. Cop 1: Fuck Due Process your ass is going in the pen.
1. To be harshly, intensely high off of marijuana and the like. Typically associated with high grade hash or kush, used in the sense that one has been hit so hard by the high that the effect is similar to a freight train slamming into them.
Man, after 4 fat ass joints, two huge grape blunts, and two fat bowls out of Jack's pipe, me and the gang were straight railroaded last night.