I somewhat suspect the funny tag will become a ghost town pretty quickly. The reason people add these funny lines is because of their juxtaposition with the realistic ones, and I think making it a recognized, expected thing with its own "space" might be missing the point.

That's not to say that something shouldn't be done about the troll-y submissions. Just making the point that a change to a system may have an unintended effect on how people use the system.