What do you take me for?
Do you think that I'm stupid or naïve? Usually followed by "a fool," "an idiot," or some such denigrating term. A: "Are you sure you installed the software correctly?" B: "Of course I did, what do you take me for?" I know that you're lying, Mike. What do you take me for, a complete idiot?
what do you take me for?
What sort of person do you think I am? For example, What do you take me for, an idiot? This expression dates from the mid-1800s.