How does he know if you've been bad or good?

This was supposedly written for and sung at a US Department of Justice, Office of Legal Counsel Christmas party during the Carter administration—please let me know if you have more precise attribution:

You’d better watch out,
You’d better not cry,
You’d better not pout;
I’m telling you why.
Santa Claus is tapping
Your phone.

He’s bugging your room,
He’s reading your mail,
He’s keeping a file
And running a tail.
Santa Claus is tapping
Your phone…