Noun.) A dump so large that it piles up in the toilet to the point it breaks the surface of the water resembling a cat sitting on a stool. Furthermore a Stoolcat can be sub-categorized depending on its physical attributes. i.e. The Calico Stoolcat (Corn and Water Chestnuts) The Siamese Stoolcat (Grey in color) etc.
Shawn: "Dude, was that you that just left a stoolcat in my toilet?"
Mike: " Ha! Yeah, i know how much you love those little guys!"
Jake: "Oh my god I have to crap so bad i bet i'll leave a stoolcat!"