Currently joke tags are kept "because they are fun". Most of them don't actually provide any function at all (there's a few that do, like the pinkie_pie_out_of_fucking_nowhere tag, or lost_my_keys, for another, but for the most part, they don't actually, well, do anything other than be a meme for the sake of being a meme, which we already deny images of).
I bring this up for consideration, for joke tags getting their own catagory, since they aren't exactly general tags following the general tagging guidelines. It'd also legitimize them somewhat, and give users looking for a laugh a specific section to look at for such things. It'd also stop issues with trying to remove joke tags in general, especially when sometimes joke tags do get removed through the normal process, currently, which makes it feel arbitrary rather than properly supported.
Updated