You have no idea 

A response that emphasizes the irony of the preceding statement.

Woman A: Your husband is unfaithful?
Woman B: You have no idea. (Husband has a gay lover)

Man A: Heard you a crazy weekend!
Man B: You have no idea. (Man B is a secret agent who used a party as a cover for a mission)

You have no idea by Urban LXX November 1, 2015

You have no idea 

A phrase used by people who have no comprehension of a situation that is passively put back on the others in the conversation and when asked to elaborate, cannot.. They say 'you' have no idea when they really mean 'I' have no idea.

How was the math test?

Oh, you have no idea.

That's why I asked. tell me about it.

<Blank stare>

You have no idea by Bar Bastard June 11, 2011

I have no idea what you're talking about 

The most self-incriminating thing a suspect can say to a law enforcement official.

A suspect who has a substantial amount of evidence linking him/her to a crime will act completely oblivious to the matter.

Saying such a phrase will destroy a suspect's credibility since he/she is being non-cooperative and is obviously lying.

Officer: We've got your DNA on the dead body, your fingerprints are all over the murder weapon, and we have three credible eye-witnesses saying they saw you pull the trigger!

Suspect: I have no idea what you're talking about.

Officer: Thanks, that's all I needed to hear.

I have no idea what you're talking about by YouAndMeInJapan June 30, 2011