expression: know your zs?


When I watched the criminal minds 1x01 episode, the guy (unsub) said to the girl (victim) while he tries to sell a car to her.

“You know your Zs. I’m impressed.”

I think it means maybe she knows a lot about car like, a to z. I guess this in the context but I’m not sure. What do you think?


According to the script at: , the car is “a red Datsun Z”. So, I guess he’s just saying that she knows a lot about this model of car.