What is a meme?
Wikipedia explains it better than I can: http://en.wikipedia.org/wiki/Internet_meme
By "facebook memes," I was referring to the statuses that spread on facebook by people copy and pasting them to their own statuses (they usually encourage the people reading it to post it as their status to pass it on). They're kind of like facebook chain letters. Some are just supposed to be fun, but others claim to be raising awareness for some cause, like breast cancer awareness.