When you have to take a shit so bad, and so large that it starts occasionally peeking out of your butthole. This usually occurs when your diet is mostly composed of meat. Not to be confused with prairie doggin' it, ground hoggin' it is much larger than prairie doggin'.
I had to shit so bad the other day that I was ground hoggin' it.
This comes from highschool football(American) when the extra point is about to be kicked. Some highschools use a tee to hold the ball after it's snapped, although most do not. If a kicker doesn't want the tee, he asks his coach to remove it and kick it as it was meant, off the ground.