What are the lyrics to I saw Mommy kissing Santa Claus'?

I saw Mummy kissing Santa Claus
Underneath the mistletoe last night.
She didn't see me creep
Down the stairs to have a peep;
She thought that I was tucked
Up in my bedroom fast asleep.

Then, I saw Mummy tickle Santa Claus
Underneath his beard so snowy white;
Oh, what a laugh it would have been
If Daddy had only seen
Mummy kissing Santa Claus last night.