September Tropical Sticker Storm
As your guests arrive, give each one a sheet of 10 tropical stickers (palm trees, coconuts, the works). Tell everyone the goal of the game is to place all 10 stickers on guests without the guest catching you. If you are caught by the person you're trying to sneak a sticker on, they get to put one of their stickers on you. The person that gets rid of all their stickers first wins....and definitely deserves a tropical cocktail for being so sneaky.