A U.F. Grant Original!
Show a colorful metal tube with two solid steel spikes penetrating through it. They are really through the tube! Remove the spikes for examination. Place a balloon in the tube, and blow it up filling the tube until it sticks out from both ends. The spikes are now thrust through the tube exiting the opposite side! The balloon is clearly seen penetrated by the spikes! But will not break! Explain that? Pop the balloon with a pin, the spikes remain penetrating the tube!
Provide your own long balloons!
Tube colors may vary!