From Longman Dictionary of Contemporary Englishdon’t tell medon’t tell meINTERRUPTused to interrupt someone because you know what they are going to say or because you want to guess – used especially when you are annoyed ‘I’m sorry I’m late but ...’ ‘Don’t tell me – the car broke down again?’ → tell
Examples from the Corpus
don’t tell me• Don't tell me we're out of milk!• "We finally made it here." "Don't tell me - you couldn't find your keys." 