Cool examples of the Central Limit Theorem in action
Solution 1:
Find an old stone step or lintel in front of a doorway (one that is old enough that it has been worn down by generations of people walking over it). If you look at how it is worn down, the wearing down won't be uniform over the surface of the step: rather, it will be in a bell-curve. (People tend to walk through the middle of the doorway.)
If the door doesn't open all the way, the bell-curve won't be perfect; there will a bias towards the side away from the hinges.