To dismiss someone else's statement that either corrects, or nullifies your previous statement.
"I'm not sure we're going the right way."
"Hey! You don't tell me!"
by Zias Noxid April 6, 2009
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Another way of saying, "I understand" or "I already know."
(patiently listens to a broken man's pitiful, self-depreciating speech)

My Response: "You don't have to tell me twice and I'm okay with it as long as you stay away from my sis. P.S., Jesus loves you and everyone else thinks you're an idiot."
by ms.understood September 17, 2013
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