This really is a Holiday party idea. We held an April Fools party that eveyone is still talking about.  The party was held in our basement. We turned off the entire up stair lights in the house making it look like no one was home.  I had a note on our front door telling guests to enter through the man door of our garage.  We had out daughter's baby room monitor in the garage so we could hear when people were coming in and those of us already in the basement would keep quiet.  In the garage I had an assortment of crazy hats.  The hats varied in style, hard hats, straw hats, hunting hats, Mickey Mouse ears hat, several hats of my Dads from the 60's, sombrero's, a sailor hat, we had almost every combination of hats one could think of.  By the hats was a sign explaining that everyone must choose a hat to wear before coming in. Mind you, we had the listening end of the room monitor in the basement with us and we really had a chuckle listening to people talk to one another as they chose their hat preference!  Once the hat was selected, guests would enter the house into darkness.  I had lined a pathway to our basment door with some yellow caution cones my Dad use to sell, one could easily use some bright color flagging tape purchased at Lowe's or Home Depot to mark a pathway. Us basment dwellers would keep quiet until the guests had come down and joined the fun of the party. Then we would wait for the next victim to choose their hat and come on down! Throughout the evening I had people switch their hats. It was quite amazing how people became attached to "their" hat and didn't want to give them up, but they eventually did.  By the end of the evening and after several switches I asked people to take their hats off once more as I had tagged several of the hats for "booby" prizes.  It was so much fun seeing who chose what hat, especially our more conservative friends and the hats they had picked to wear.  Everyone had a great time!