My idea is the following... You should invite for your party Santa Claus, who at the beginning of it would behave in a common way - give presents, tell some magic fairy-tale, for instance describing his way from lapland to your house.... But in some hours, this Santa Calus should choose a right moment and reshape into...well, say.... a hot macho...singing serenades for your quests...or into a sexy seducer...Here you are free to invent your own "scenario"...
I am sure your guests will be quite surprised and this episode should add some fun to the party...