I am guilty of the first joke reply, but consider:
- The thread is in the clown house.
- The title of the thread is itself a joke.
- The first post fills one's screen with a joke picture.
- The first post's first paragraph apologizes for being long-winded so does not encourage careful reading.
It was hard NOT to reply with a joke to an "obviously" joke thread in a humor forum. I didn't even read the first post until after I replied to it.