Check out this awesome video created by The Gag Quartet which has 40 memes in one song.
I can’t even count all 40, can you?

What is a meme?

According to the Urban Dictionary it is:
1 : an idea, belief or belief system, or pattern of behavior that spreads throughout a culture either vertically by cultural inheritance (as by parents to children) or horizontally by cultural acquisition (as by peers, information media, and entertainment media)

If you want to know more about memes check out one of my favourite sites called Know Your Meme -a website dedicated to documenting Internet phenomena: viral videos, image macros, catchphrases, web celebs and more.