There is an old Bing Crosby (?) version that has a more swing rhythm tune, which is fun to sing.

Christmas is a'comin' and the goose is gettin' fat
Please to put a penny in an old man's hat.
If you haven't got a penny then a ha'penny will do.
If you haven't got a ha'penny then God bless you.

Chorus
God bless you, gentlemen; God bless you!
If you haven't got a ha'penny then God bless you.

It goes one Christmas ... and the light's are on the tree.
Hang up your stocking for everyone to see.
If you haven't got a stocking then a little sock will do.
If you haven't got a little sock ...

This song is sometimes included in popular Christmas Song collections and fairly easy to find. A Kindergarten teacher I worked with taught it to me.