A notorious car in a neighborhood that cruises around crowded streets, in which the driver sells pot out of his car. Very easy to find, the "grain train" is usually a dude who will roll down his windo no more than 6 inches from the top, take fifteen bucks, slip you some weed and roll out.
You got any money, cuz the grain train is driving away.
A name for a hardcore crew of party-goers who often arrive at drinking parties equipped with one or more bottles of Golden Grain (or Everclear) and some grape soda or similar beverage to mix with the Golden Grain.
The party was dying, we were drinking beer and running out, but then the grain train showed up and we partied our asses off and all got fucking HAMMERED!