Define I Dont Know, I'm Not A Doctor Meaning

I Dont Know, I'm Not A Doctor
A sarcastic reply to a very obvious statement or situation.

Gerry: So you stayed up all night eh?
Phil: Yep and I feel really sleep deprived.
Gerry: Really? You know I heard sleep was a good way to treat sleep deprivation, but again I dont know, I'm not a doctor. I might be wrong.

Andrew: Hey look! It's raining outside!
John: Yea I heard it tends to happen every once and a while....but again I dont know, I'm not a doctor so don't take my word on that.
By Grace