Huh, I guess it's one of those "had to have been there things", because I'm not seeing the humor.
Fair enough, I mean after all, "meme" comes from the theorized "memetic", a unit of culture. If you're not a part of the culture in which a meme originates, the spread/mutated form can be confusing for an outsider to understand. Think about SomethingAwful, a lot of popular internet memes come from there, but a good number of their memes and catchphrases are theirs alone because most of the site is only visible to paid members.
Also, when I was fact-checking, in a brief moment, the wikipedia page was vandalized to have "Y U NO" in the first sentence. Perfect example of how far things can spread.