When I was finished she said, "Now three for Mommy."
Having absolutely no idea what that meant, I questioned her: "Three what for Mommy? Three pieces of cake for me? Do you want me to sing Happy Birthday for Mommy?"
"Yes, three for Mommy."
Still confused I gave it a go and let out a weak "Happy Birthday to You" and was promptly interrupted.
"Three what, I don't understand?"
It went on like this for a while, until I finally got it, and correctly sang:
"Happy Birthday Three You,
Happy Birthday Three You,
Happy Birthday Dear Mommy,
Happy Birthday Three You."
Because as Amelia astutely observed, this is the proper encore after a round of "Happy Birthday Two You!"