(After watching the Max & Ruby episode where Ruby is out selling brownies for her scout troop. — think Girl Scouts and cookies)
Brother: Mom, mom! Can we get Bunny Scout Brownies?!
Me (with sympathy): Oh, honey, I’m sorry Bunny Scout Brownies are just pretend.
Brother: Nonsense!
Sister: Did he just say “nonsense”?
Me: Yes, he did.
Sister: Hmm, pretty grown up word for such a little boy.
********
Yep, they’re mine.

Isn’t that awesome? My kids have unusual vocabularies as well–enough that my inlaws will deliberately ask them questions on video camera so they can capture them speaking. It is just a result of being around adults all day who talk to them and don’t dumb down their vocabulary but it is really awesome and cute.
(Just yesterday I heard my 6 year old son use illustration and appropriate in sentences.
The only thing that’s better than Brother saying “Nonsense!” is Sister’s very grown up response. Your children are precious and so smart!
I taught my nephew to say “ambidextrous” when he was about 2. He’s not “that word” and he didn’t know what it meant, but it was so cute to hear him say it! I must have pushed him over the edge at some point, though. He’s now 5 and he refuses all efforts to get him to say my favorite word any more.