You'll be sorry you asked

You'll be sorry you asked.

Inf. The answer to the question you just asked is so bad that you will be sorry you asked it. (Compare this with (Are you) sorry you asked?) Father: What are your grades going to be like this semester? Sally: You'll be sorry you asked. Mary: How much did you pay for that lamp? Jane: You'll be sorry you asked.
See also: ask, sorry