Maybe they do carry that...

At the library today, reading Breanna a book about trains...

Me: Some cars carry gas, some carry grain.

Breanna:  Gas and grain.

...more similar pages, read out loud, mind you...

Me: Some cars carry metal, some carry scrap.

Breanna, loudly: Metal and crap.  (And no, she doesn't actually know that word!)

I laughed so hard I almost peed, which doesn't take much right now.  :-)