Tie a piece of string around wrists of your "victim" (one of the boys in your den). Loop another piece of string over your victim's wrist and tie it to your wrists. You are now locked together. Challenge victim to get away without breaking the string or untying a knot. When he gives up, show him how. Push the center of your string through the loop on the inside of your victim's wrist, bring this new loop back over his hand and draw it back through the wrist loop. You will be free. For double fun, tie two victims together in the same way.