Choo choo pants

Esmé has some training pants underwear that she sometimes wears them over her diaper and I bought them for her to wear when she refuses to wear a diaper around the house. 

Well she will occasionally call them "choo choo" pants and I was never sure why, then today it all clicked when I said, "do you want to wear you training pants?" And she said "yes, my choo choo pants". I guess hearing me say train makes her think choo choo. 

Very funny girl.