I’m honestly very confused by it. This rules make less and less sense to me everyday because the creators werent clueless idiots, damn near every post here was intentionally funny? Do you mean no humor only comics or obvious jokes?
Or is it if the character is saying it to make a joke or trying to be funny? Is it fine if the writer/artists intent was to be funny?
It’s generally hard to guess at authorial intent, but the smurfs one isn’t any more dirty than the rest of the smurf language, in context. Here’s the full page:
Here’s another few panels from that issue that shows how often verbs are replaced with “smurf”:
If you replace that many verbs with “smurf”, eventually you’re going to end up with something that sounds dirty. In context, it reads as very normal speech though. Maybe the author knew that and secretly did it intentionally, but the general audience wouldn’t have interpreted it that way.