I love these situations:

I’m picking up my daughter at her child-minder’s. The other little girl in her care, J., a few months younger, has brought her tricycle, which is parked near the door. (Incidentally, it’s identical to hers. When she opened the door for me and saw me wearing my bike helmet, then the tricycle, she looked from one to the other and said “C’est pas vélo maman.” – That’s not mommy’s bike.)
Her daddy is one of those people who will call tricycles “bikes” (vélo in French) at least when speaking with the kids. As I’ am trying to establish a correct vocabulary, I told my daughter “Das ist kein Fahrrad, das ist ein Dreirad.” (That’s not a bike, that’s a tricycle.) Whereupon she turned to the vehicle’s owner and told her “C’est pas vélo, c’est Dreira’!” – That’s not a bike, that’s a tricycle!)