You want a what?

This morning Sydaleigh came into our bedroom, climbed atop the bed, laid down to snuggle, looked at Isaak and said, "Daddy, I want a pony."
over and over and over again.
It was so cute we were busting up laughing because we had no clue where that even came from.
A pony?!
I think it's pretty much a given that every little girl is going to ask for one of those, but I thought we at least had a few more years.