an abnormally large feces left behind in the toilet and is either a)unflushed or b)will not flush. The person responsible for leaving said gromer behind is called a Gromeo.
Dude who left that gromer in the toilet? I don't know who it was but he was a damn Gromeo. That thing had a whole ear of corn in it for sure.
Man I gotta get to home base soon, I feel like I got a gromer on deck