If you see a tree that you want to stand under to take a break while hiking, a good parent will stand under the tree with you. This is a kind and caring parent who can see that you are tired and want to relax by standing in the shade of this tree.
Once you get closer to the tree, you and your parent see that it has some pretty crazy roots coming out of it. While making your way into the shade, you manage to bang your shin (しん) on one of these roots. Your shins already hurt from walking so much, and this is just icing on the cake.