Can the jokes be about winter as well as Christmas?
Cos if they can I could tell the joke about the guy who saw a yellow patch in the snow on his front lawn. On closer inspection he realised there was a man's name written in the middle.
Pointing it out to his neighbour he said; "Look at that! I'll kill him when I lay my hands on him."
"Calm down, you were young once - are you telling me you never wrote your name in the snow after a few pints?"
"It's not that - that's my wife's handwriting!"
But if they have to be about Christmas I'll tell it on another occasion.