> Even if you agree with not watching porn at work on principle, it's weird to have it as an explicit policy. It's like if the employee manual has a "No stealing the office supplies" or a "No office fight-clubs" policy.

No personal use (with incidental use exceptions for some items, and often exhaustive examples of what is and isn't incidental) of company property and zero tolerance for workplace violence of any kind policies are pretty common, IME.

Sure, and if there was a policy of no sexual harassment including openly watching porn, wearing sexually explicit apparel, or discussing your active sex life and a policy of no using your employer's internet for personal matters other than direct communication with family and friends, especially calling out watching porn, pirating digital media, or playing videogames as examples, that would be one thing.

It's having an explicit, naked, unadorned policy specifically stating "Don't watch porn on company time" not in the context of an umbrella policy that's strange. Much like having an aside "Also don't start a fight club please" or "By the way, don't stuff your bag full of office supplies" would be weird.

They’re common expectations, not common policies. Whenever there’s a policy, it means someone did something, and they had to make a rule.

No sunbathing on the roof.

No eating the office supplies.

I’m certainly going to create a

  No office fight clubs
           - Management

and hang it in the next office I visit.