Where a fat guy doesnt have a stomach hanging in front of him like a beer belly or a keg its a big piece of skin hanging down to his waist or his knee's. Like the flaps on the back of the truck
You anda friend see a guy who streaches and lifts his shirt and all you see is skin not even shaped hanging down.
Your Friends says "Ew he doesnt even have a keg"
You say "No joke it looks like a Mud Flap hanging down like the back of a truck.