A combination of the words poop and torpedo. Used to describe a poop that is projected from the anus so quickly and stealthly that it is in a torpedo-like fashion.
Tristan was impressed with the velocity with which his poop was expelled and exclaimed "Mom, a poop-pedo just shot out of my butt!"
When you use a public restroom and its so nasty you squat over the tank and drop a shit in it.
Man that gas station toilet was as so fucking nasty I had to drop a poop-pedo.