Saying you don't know:
* I don't know. I think it's...
* I'm not sure. I think it's...
* Sorry. I don't' know.
* I'm afraid. I'v no idea.
* I can't help you there.
* I don't know anything about ...
* I haven't got a clue.
* Search me.
* Don't ask me.
* What are you asking me for.
* How the hell should I know.
*
