whistle in the dark
in. to guess aimlessly; to speculate as to a fact.Am I close, or am I just whistling in the dark?She was whistling in the dark. She has no idea of what's going on.
Your guess is as good as mine.
sent. “I don't know either.”I don't know. Your guess is as good as mine.Your guess is as good as mine as to when the train will get in.