You think you've got it
Oh, you think you've got it
But got it just don't get it when there's nothin' at all
You normally use "got it" at the end of a sentence when you are reprimanding someone.
Example: Go pick up your shirt, got it? It is an angry way of speaking to someone. Do not use "got it" when you are speaking to someone in a friendly or respectful manner as you will sound rude.
You normally use "get it" at the end of a sentence when you want to be more friendly or respectful.
Example: When you are talking with someone and you want to politely check if they understood what you said. You can ask: "Did you get it?"