mash potato mouth

The action in which one tries to speak and a fully formed sentence is not formed. There are fragments and random words. The person is intently trying to form a sentence and make a point, but the sentence is incomprehensible. There is usually an utter of words and the spew of grunts and/ or the word uhh. This action is usually accompanied by a blank stare or glazed look.

I went to talk to him, but he started mash potato mouthing everywhere. He is real hard to talk to.