When your weight is distributed between more than one object, even seemingly delicate things can support you. Watch a young scientist friend of mine build a tower out of paper cups that she can stand on! How high can she go?
You can easily try the same thing at home! If you try standing on a cup tower, you have someone with you to help you get on and off and to help you stay balanced. As you can see in our hastily built tower, it started to get wobbly as it gets taller. We only had enough cups and cardboard sheets to go six levels high. How high do you think you could go if you had even more cups to work with?
If you make a tower yourself–and I hope you will!–notice how much more stable the tower was when we were building with 12 cups per level. That is the best technique. 12 cups will even support the weight of a 150-pound adult.
The principle behind this is the same thing you experience if you try walking on eggs, or laying on a bed of nails. The more objects in contact with you, the less weight each has to bear. This allows you to stand on cups or delicate eggs, or makes the pressure against those pointy nails to be too small to damage your skn. Leave the bed of nails to experts, though. Ouch!