At least an ounce of marijuana or a growing marijuana plant. Rooted from "Red" (weed) being exchanged for "green" (cash) and "Roman" referring to a large or growing object (like how the roman empire was always growing and/or was generally large.) Hence: "Roman (1 oz.+ or a growing plant) Red (marijuana)"

When you eat dirt for the first time and leave your family to build a shack in the woods