My 70+ year old auntie told me this joke years ago. It still makes me laugh.
Santa emerged from a fireplace and in front of him was a beautiful young lady wearing only a short negligee. She slipped it off one shoulder and said, "Won't you stay and keep me company on this cold Christmas eve"?
Santa replied "No, I can't. It's Christmas Eve and all the children who've been good are waiting for their presents".
The girl then slipped off the other shoulder and asked Santa again if he would stay with her. Santa repeated that he couldn't, as all the children were waiting for him and he didn't want to disappoint them .
The girl then let the negligee fall to the floor and said, "Won't you stay now and keep me company"?
Santa looked at her and said, "I may as well, cos I won't be able to get back up the bloody chimney"!