I heard of a forum (I don't remember the name of it) and if you reply to a troll, you are banned, even if you didn't know the user was a troll.
On Wrongplanet, if you talk about a member or mention their user name and they were banned, you get warned or reminded of the rule because one of the rules is "No discussion of banned members" and you still get warned or reminded of that rule even if you didn't know that user was banned. The problem is, some of the moderators take the rules too damn literal because of their AS and they expect you to read their minds. But now with lot of the bad ones demodded, the forum should be better.
On Nsider2 forum you are not allowed to reply to threads that haven't been replied to in over a week or they consider it a thread bump if you do it.
On Hikiculture, my friend who owns the forum decided no more anime avatars and anime sigs.
So ever been to a forum that had ridiculous rules? Share them.