Ok I can understand Final Fantasy. Though I only played 789, I know this and that about every other absorbed through osmosis.
I can even understand Spider-Man. I don't care about capeshit or marvel at all. But I know Spider-Man, the gist of it. I've seen the 90's cartoon. I've seen the movies with Toby.
But Avatar? Is Avatar really so popular? The only thing I know about Avatar is that the fire nation attacked at some point.