Ongoing Battles Of Will: Phrasing Feud

D and I were talking. He says I use too many "big" words.  I think I use just enough.  I like words, they are fun.  Here's part of the convo:

D: How did you know...?

Me: You know, I can extrapolate data from incomplete sources. 

D: You mean you can figure stuff out.  Why do you talk like that?

Me: I dunno.  'Cause I'm smart?  Because I want to express myself clearly by using appropriate
       vocabulary?

D: You mean you want to be understood?

Me: That's what I said.

D: No, you used more words than you needed to.

Me: I think I used the appropriate numbers of words to convey what I was thinking.

D: You're doing it again!  You're being verbose.

Me: No, I am not. I have a large vocabulary, and I find challenging myself to use words that are
       frequently misused or forgotten, fun.

D: Okay.  You say "potato..."

Me: ...I say "subterranean, starchy, tuberous, crop."