any idea or behavior that is in any way replicating an idea or behavior previously observed is a meme
posting on the internet is a meme
putting on clothes is a meme
language is a meme
shaking hands are a meme
smilies are memes
using keyboards is a meme
news networks are memes
politics is a meme
pretty much everything created by humankind (and even learned behaviors in non-humans), is memetic in nature