What determines something becoming a meme?

What determines a piece of media or whatever to become a meme and will everything be turned into a meme into the future (if it hasn't already) I've heard songs and seen episodes, clips, and entire TV shows and movies that no one cared about before but them all of a sudden people turn them into memes and they blow up in popularity. I'm just convinced that everything is going to become a meme at some point. While on the topic, what piece of media are you suprise hasn't become a meme yet and what piece of media do you think should be made into a meme?