"Santa Claus Is Coming to Town" (sometimes with Coming changed to Comin') is a Christmas song. It was written by J. Fred Coots and Haven Gillespie, and was first sung on Eddie Cantor's radio show in November 1934. It became an instant hit with orders for 100,000 copies of sheet music the next day and over 400,000 copies sold by Christmas.
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Santa Claus Is Coming To Town

I just came back from a lovely trip along the milky way
I stopped off at the north pole to spend the holiday
I called on old dear santa claus to see what i could see
He took me to his workshop and told his plans to me

Oh! You better watch out,
You better not cry,
You better not pout,
I'm telling you why:

Santa Claus is coming to town!

He's making a list,
He's checking it twice,
He's gonna find out
who's naughty or nice.

Santa Claus is coming to town!

He sees you when you're sleeping,
He knows when you're awake.
He knows when you've been bad or good,
So be good for goodness sake!

So...You better watch out,
You better not cry
You better not pout,
I'm telling you why.

Santa Claus is coming to town.

Little tin horns,
Little toy drums.
Rudy-toot-toot
and rummy tum tums.

Santa Claus is coming to town.

Little toy dolls
that cuddle and coo,
Elephants, boats
and Kiddie cars too.

Santa Claus is coming to town.

The kids in Girl and Boy Land
will have a jubilee.
They're gonna build a toyland town
all around the Christmas tree.

Oh....You better watch out,
You better not cry.
You better not pout,
I'm telling you why.

Santa Claus is comin'
Santa Claus is comin'
Santa Claus is comin'
To town.