The closest thing to a rooster that Abby interacts with regularly is Polyphemus the Starling, and perhaps she’s extrapolating the pooping habits of roosters from that.
TEXT OF COMIC:
It’s good to be back here at the dorm. That was a long class. I have to pee like a racehorse.
And I have to poop like a rooster.
Caca. Doodoo. Doo.
I am going to pretend I didn’t hear that.
roosters that pee are called peecocks