We've taken a bowl of uncooked rice and pour some small closed safety pins in it and mix it up. Blindfolded people then stick one hand in and pull out as many safety pins as they can in a measured amount of time....like 30 seconds. It's not easy to pick those safety pins out without looking and one hand. The one with the most safety pins wins.
Take a roll of ribbon and ask each person to pull off as much ribbon as they think will be the right size when wrapped around the expectant mother....around her waist and the widest part of her belly. Who ever is closest wins.