used to introduce a question; Used in "you tell me" to throw a question back, meaning the other person should already know or must answer it.; Used in "tell me about it" to agree strongly or show you have had the same experience.; Used in "don't tell me" before unwelcome news to show dismay, disbelief, or that you hope it is not true.
Oxford55% of films
used to introduce a question
Editorial5% of films
Used in "you tell me" to throw a question back, meaning the other person should already know or must answer it.
Editorial5% of films
Used in "tell me about it" to agree strongly or show you have had the same experience.
Editorial5% of films
Used in "don't tell me" before unwelcome news to show dismay, disbelief, or that you hope it is not true.
Definitions from the Oxford Advanced Learner's Dictionary, 9th edition