This is a messy game, really messy. But it is also a strong bet for the game the kids will most talk about after your Halloween party.
Get one pie tin for each party guest. Put 8-10 gummy worms on the bottom of the pie tin and then add a layer of whipped cream. Add more worms and then top it off with more whipped cream. Make sure that you put the exact same number of worms in each pie and 2-3 worms are sticking out of the whipped cream when you add the final layer.
The contestants sit at a table with their pie tins filled with worms and whipped cream in front of them and a plastic cup next to the pie tins. The object of the game is for the guests to take the worms out of the pie tins and put them in the cup. The catch is that they must keep their hands behind their backs and only use their mouths. Give them a Ready, Set, Go and they have 30 seconds to move as many worms as possible from the pie to the cup. The person who has the most worms in their cup is the winner and gets a prize.
Obviously this game is best if played outdoors or in an area that is easily cleaned. A good supply of towels and other products for wiping down the players afterwards is highly recommended.