>>913882So in the US (and I'm sure in other parts of the world) there are yards called "hump yards." And within these yards exists a hump. which is really just a hill that they've made up. So what you do is shove cars up this hill, pull the pin at the crest and let them free roll down the hill into a prescribed track.
Some cars and commodities are more delicate than others and letting cars free roll into others isn't exactly a soft coupling. Thus, they will be stenciled with "DO NOT HUMP" upon their sides so that crews will know to shove them to a couple.
Furthermore, it is also inadvisable to kick cars stenciled not to hump. Basically you're just not supposed to let them free roll.
Hope that helps.
