Chuck Norris is...
What? You don't need to know what he is. He's just, Chuck.
He's Just Chuck
Explanation
Explain Bear
Listen here, lil' snowflake. This ain't rocket science. The 'joke' is that Chuck Norris is so powerful and legendary, you don't even NEED to describe him. He's just... Chuck. It's like saying water is wet, or you are not very smart. Everyone already knows.