Internet memes attempt to create humor by taking something, be it a phrase, picture, facial expression, or concept, and saying, doing, or repeating it over and over again with occasional variations, on the off-chance that sooner or later, something funny will be produced.
Furthermore, these days internet memes are pretty much all completely forced; unlike concepts that evolved naturally into the public consiousness (for example, the Rickroll, which started as a surreal one-off joke), pretty much any internet meme you see today will have been started with the sole purpose of creating an internet meme.
Real humor doesn't rely on force-feeding you something over and over again to be considered funny. Real humor doesn't need to be spread to hundreds of people on 4chan or reach internet stardom to be considered successful.
Glad to answer your three-month-old question, Wiggles.