You get a stick, and you find some half-dried mud. Could be a mud puddle after it rains. Then you crouch down, and you poke the stick into the mud. Keep poking the mud. Sometimes the mud sticks to the bottom of the stick and comes up in a clump, but sometimes the stick comes up dry. You can draw marks in the surface of the mud with the stick. It's like an Etch-a-Sketch. You can try to stand the stick upright in the mud so that it doesn't fall over. But please, don't eat the mud. I know it's tempting, but don't eat it. Bad for your teeth.