A very difficult Gay sexual act normally consisting of 6 gay men in an
orgy. Four of the men are having anal
sex , all while underneath them the other two men assume the ball licking position as the other men are fucking doggystyle. In order for the position to work the two men getting it in the ass should need to take a huge shit , or have a bad
case of the runs. Immediately after the two men servicing the ass givers
cum in the buttholes , the guys who took it in the ass then proceed to shit on the receivers down below .
Hence the phrase Gravy
Train because its a bloomin Shitty Gravy like mess afterwards.