Not know somebody from Adam
Definition 1 of 1
Pro Tip 1/3Literal Meaning
The phrase is not about Adam; it's a way of saying you don't recognize someone. 
Even though we worked in the same office, I wouldn’t know her from Adam.
Pro Tip 2/3Complete Stranger
Use the phrase to emphasize that someone is as unfamiliar to you as it's possible to be. 
The man in the photo could be anyone – I don’t know him from Adam.
Pro Tip 3/3Astonishment
It often shows surprise that others expect you to recognize the person. 
You know Mike from accounting? I don’t know him from Adam!