Common sense dictates there are just certain rules you follow with respect to someone else’s child. You don’t spank another parent’s child. You don’t take another parent’s child to the salon and get blue and green streaks in the kid’s hair without the parent’s consent. You don’t sign consent forms for someone else’s child to get body piercings or tattoos.

You also don’t breast-feed another woman’s infant without her knowledge.

UPDATE: Whoops, folks, we may have a tie since common sense also says you don’t call in a bomb threat just to make sure your plane doesn’t take off without you.