Shut up, you don't know anything.

Shut up. After someone says it the next words felt or hear are, you don't know anything. Seth Godin came at it in another way in his blog The expertise gap.

Whatever is said before shut up might be so different from what is understood, it can't be understood, so it can't be heard, so the words shut up come out.

You don't know anything, can sound more like an admission of not knowing what you know, if it's heard, felt, knowingly.