There was a similar thread to this on here once before and someone posted a story in a very similar vein.
His Mrs was making cakes with his young daughter when little girl piped up
"remember when we used to make cakes all the time"
as this was the first time she had ever made cakes with her daughter the lads Mrs replied "No, when?"
The little girl said "ooh years ago, when you was a little girl and i was your Grandma"
I can't remember who posted it but it shit me up big style as one of my daughter used to say some weird shit when she was young.
She would say things like "when i was older i used to....." and "when i was a big girl like mummy i went there"