This is 3 or more people spooning in the same direction to either preserve heat or reduce the space taken up in a cramped area. It is a manoeuvre most often performed by teens.
eg- "its a 3 man tent and theres 5 of us... time to spoon train"
Affectionatecuddling where someone lays behind another person, usually with both people being in a fetal-type position and arms wrapped into the chest. A spoon train is a line of more then two people spooning.