This is the act of human fecal matter ( stool, turd, brown trout) slightly protruding out of the anus and then immediate retracting. This happens in humans but animals as well. It is the result of the person or animal needing desperately to defecate but for some reason cannot find facilities or the right place to evacuate the waste. It may happen many times before final evacuation. The term achieved it's name from prairie dogs being observed going in and out of their habitat.
note: As a result, in humans, this act can also cause another situation call "skid marks" which is the evidence of the PD stain left on the persons underware, other clothing or anything next to the anus where the Prairie Dog emerges.
"Hey mom, we have to stop at the next gas, Billy's got prairie dogs".
"My girl must have had prairie dogs tonight cause when we had sex I saw skid marks on her undies."