This can be for kids, too, but works better with teenagers or adults.  AFTER your guests have arrived, and had some time to mingle, discreetly pull them aside one by one, and give them something to put on that they didn't come with, such as - A necklace, bracelet, rings, pin/broach, scarf, belt, hat, glasses, sunglasses, fancy earrings, etc. Be creative. Plan ahead as to what you are going to give each guest. Then, at a set time, announce what the game is, and a time limit, pass out paper and pens, and have your guests make a list of WHO is wearing something they didn't arrive with, and WHAT it is. You could even have one or two NOT wear a game item, to make it even trickier. Have a nice prize for the winner, or top 3, or whatever you choose. It's ALOT of fun, and is a GREAT conversation piece. Guaranteed fun every time!