What can I tell you?
1. Lit. What kind of information do you want? Bill: I have a question. Bob: What can I tell you? Bill: When do we arrive at Chicago? Mary: I would like to ask a question about the quiz tomorrow. Bill: What can I tell you? Mary: The answers, if you know them.
2. Inf. I haven't any idea of what to say. (Compare this with What can I say?) John: Why on earth did you do a dumb thing like that? Bill: What can I tell you? I just did it, that's all. Mary: I'm so disappointed with you, Fred. Fred: What can I tell you? I am, too.