an upsized poo that is simply too large to be expelled without grunting, clenching, and the bursting of facial blood vessels.
"dropping a grunter" is the act of producing one of these intimidating steamers.
"where the fuck is stu, i'm thinking of stealing his weed"
"he's in the bathroom dropping a grunter, i can hear him struggling with it from here. yeah pack me a cone too, he's still grunting away... we'll have enough time."
"rad... LOVE the grunter"