Get a few dozen pacifiers and a big see-through container like a novelty sized feeding bottle. You can also use a jar filled with jelly beans, Hershey kisses, gumballs, or even pacifier shaped sweet tarts. Fill the container with as many pacifiers/candy as you possibly can. Make sure you count the number of pacifiers/candy as you put them in. As guests arrive ask them to look at the bottle and write on a slip of paper their name and how many items they think are inside. The guest who comes closest to the actually number wins!
If you place some pacifiers with the caps on, some without and other with the packaging it can be quite difficult to guess how many are actually inside the bottle.