Just Try To Keep Up

This conversation happened yesterday while we were driving.

Josh: Mom, did you buy anymore of that chocolate smoothie mix?
Me: Nope
Josh: You didn't buy anymore?
Me: Nope
Josh: So you didn't get more?
Me: Nope
Josh: Stop saying NOPE!
Me: Well, I already told you that I didn't buy any, so why do you keep asking?
Josh: I'm not asking if you bought any, I'm asking if you didn't buy any.
Me: Ok, the answer is nope.
Josh: Stop saying that!
Me: Well, what do you want me to say?
Josh: I want the answer to be yes.
Me: But I didn't buy any, so I can't say yes.
Josh: Well when you say nope, it's confusing to me.  I don't know what it means.  So you should just say yes.
Me: But I didn't buy any so I said nope.
Josh: But that's confusing!
Me: Just think of it this way, how do you think you spell 'nope'?
Josh: Uhhh!  I'm not asking how to spell it.
Me:  I know, I'm just trying to help you remember what nope means.  It starts with 'n-o' just like the word no.  So when you hear nope, you'll know it's the same thing as no.
Josh: Uhhh.  This is just confusing me.  I don't want you to say nope anymore.
Me: Sorry bud, I'm not going to stop saying nope just because you think it's confusing, because other people are still going to say it and you might as well figure out what it means.
Josh: But I'm saying 'you didn't buy anymore?' so you should say 'yes' if you didn't.  Not nope.

I'm not sure who won.