jack-jawed
A person who talks a lot but says nothing useful. Like a broken toaster that just keeps buzzing.
My neighbor is a jack-jawed idiot. He talks for hours about his cat’s hairballs.
My teacher is a jack-jawed know-it-all. She talks about math like it’s a religion.
My friend is a jack-jawed drama queen. She talks about her problems like she’s the main character of a soap opera.