If I said I was a liar........
Inwardly your thinkin duh ...
Outwardly your eyes dart down
To the left bend the corners of your mouth into a over  exaggerated frown
Then open palms
Shrugging shoulders wagging
Gesturing a response which reads no!
You say "I don't know.. .."
I say ok .......?
I guess that make two of us?