Mummy is bemused

Last Saturday afternoon, I was carrying some books out of my bedroom. As I wasn't careful, I dropped some on the floor.
Mummy: Oops!
Chloe: Oh my God!
Mummy: Where did you learn to say that? Mummy never taught you that and we have never used such phrases at home...

Last night, Mummy was reading together with me.
Mummy: The Fox in the Box
Chloe: The Four in the Box
Mummy: You are pronouncing it wrongly. Say it again.
Chloe: SHIT!
Mummy just stared at me speechless...