Where would I even start?

E: "I see Target! I want to buy a car."
Me: "Sorry, sweetheart. Dad buys you cars. Next time you come to Target with dad, maybe he'll buy you one, but we're not getting one today."
E: "Turn around. Let's go way back there. Go far away."
Me: "Oh, we can't leave yet. We have to stop and get Miss S a birthday present. Remember? We're going to her birthday party tomorrow at the jumpy castle place."
E: "I don't want to buy Miss S a present. She can't like presents. I can't like the jumpy castle place. I'm not a good jumper. I have fat feet. See? Look. at. my. feet."
Me: ...nothing. I got nothing. How do you counter that kind of argument?