The essence of humor

Comedy is the art of the unexpected.

This can take a while to build up as a comedian or humorist may spend some time leading his audience to expect he is heading in one direction. Then, when he makes a sudden turn, it's funny because it's unexpected.

Repetition can be one way of building up expectations, to be broken shortly thereafter. (For some of us repetition is unexpected in itself, and thus can strike the funny bone particularly hard.)

This principle can carry over to the internet, too:

But where’s the enjoyment in a meme if not from repetition?

The first time I see a cat or dog with peculiar grammar, I’m somewhere between mildly tickled and simply confused.

It’s around the third or fifth version that the humor kicks in, and it’s around the twentieth incarnation, when I think I’ve gotten tired of it but someone comes up with a truly spectacular reimagining, that I laugh the hardest.

Source: Because Internet: Understanding the New Rules of Language by Gretchen McCulloch