Well, the round (canon) goes like this:

Christmas is coming, the goose is getting fat
Please to put a penny in an old man's hat.
If you haven't got a penny a ha'penny will do,
If you haven't got a ha'penny then God bless you!^^^


another version is two verses:

Christmas is coming, the geese are getting fat
Please to put a penny in the old man's hat.
Please to put a penny in the old man's hat.

If you have no penny, a ha'penny will do,
If you have no ha'penny, a farthing will do.
If you have no farthing, then God bless you!


Bing Crosby expanded it a bit:
God bless you, gentlemen, God bless you,
If you haven't got a ha'penny then God bless you!

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