When people think about padlocks and security, they think about criminals trying to crack the combination or break the padlock open or simply cutting it off with bolt cutters.  That is, they think about defeating the padlock.

Not too many people think about the far easier thing you can do with a padlock.  The denial of service attack.  Padlock somebody's gate closed and throw away the key.  That is also a security issue, super easy, and nearly impossible to defend against.  I don't even know what to do with this thought other than to keep it in my arsenal of civil disobedience techniques along side things like removing the valve stems from someone's tires.