SACK-A-POOPIE
Usually this happens when you can't make it to the bathroom in time and the poopie makes in your pants, this is squished into a ball and when you take your underwear off it hangs down and looks like a sack-a-poopie.
Matt ate a lot of beans and now he has a sack-a-poopie
Matt likes to have sack-a-poopie for lunch.
Matt likes to have sack-a-poopie for lunch.