Get everyone to sit on each other's laps.
Everyone in the group gets in a circle, facing in, shoulder to shoulder. When the circle looks round (and it must be round in order to work) they should turn to the right and sit on the lap of the person behind them. Once they are in a sitting position (and resting) it is a good time to give them instructions on other games or activities. Then ask the group to stand up quickly. This is harder than is sounds!