Yesterday at the check-out in the local supermarket, Ella suddenly exclaimed very proudly: "Poo bum!" followed by fits of laughter.
It was so hard not to join in with the giggling. But of course I had to look stern and unimpressed and had the "things that are funny when you tell your friends are not always funny when you tell grown-ups" talk.
She just looked confused and I don't blame her.