A meme-able photo of a very young child fist-pumping triumphantly in a green-and-white shirt is often referred two by what two-word phrase that starts with the letter S?

The term meme was introduced in 1976 by British evolutionary biologist Richard Dawkins (author of "The God Delusion"). He conceived of memes as the cultural parallel to biological genes and considered them as being in control of their own reproduction.