Their vocabulary is so rich! 
"What does that mean?" Is what I would say to Joe a lot, and now, my home life just goes in circles because Moonflower also naturally uses sophisticated words that catch people off guard.
It's extremely cute though because she's been like this since she first started talking; I remember she was about 2.5, put some Legos together and said "I made a semi-circle."

She's been using phrases that would have the family like, wow, and then everyone would start laughing because either someone wouldn't know what the word means and they'd be much much older, or, even if you know what the word means you be like dang! 

Just today we were talking about weird dreams and I can't think of the word she used but I think it was "ominous." It was a unique word though and I was like wow girl you talk just like your dad.

Edited to add: Just thought of the word, it was "surreal." I was just saying my 'weird and bad dreams', she said her surreal dreams. I love it.

Here are some other examples:
Incandescent Christmas lights

-----
So many cool examples that I can't remember, but there will definitely be more to come