If it is twice the height of your knees, it is a perfect hiding spot in a game of Hide and Seek, if it is three times the height of knees, you have a chance of becoming Atlas as you can position yourself in a similar manner as depicted in Classical art.
In the context of a game of Hide and Seek, a spot that is twice the height of your knees would be an excellent hiding place. If it's three times the height of your knees, you might be able to emulate Atlas by positioning yourself similarly to how he is depicted in Classical art.