Rules? We don't need no stinkin' rules.... ( in my best Blazing Saddles voice)
Seriously, however we have always been respectful knowing we have many members that check in from work and places where a picture of a couple of loose puppies could cause them trouble.
Usually if someone post something "risky" they will start a thread and put " not work friendly" in the thread title. So members can choose to not open it at work. That has always worked in the past.