Mods: Here's a vague new rule we're enforcing
Posters: Can we have some clear guidelines so we don't get banned at random?
Mods: WOW SUCH HORRIBLE PEOPLE WHAT'S NOT CLEAR ABOUT IT YOU NEED TO GROW UP.
Any actual rule would be too much for you people.
In any case, I would prefer we avoid any language that would look undesirable should a member of the Secret Service stumble upon us. That ought to at least be the starting point. It is my experience that the type of people who try to incessantly sniff out loopholes face certain character deficits.