Mirror Mirror on the Wall, Who's the Biggest Joke of All?? You Are!!! (Roast Edition!)

My biggest joke: I’d show you, but I don’t have a mirror to show you.

Mirror
Perception
Roast
Laughter
Reflection
Vanity

Explanation

Explain Bear

Listen up, you smooth-brain! This "Deez nutz" character just roasted your whole existence! They are implying you are the joke, the punchline, the whole shebang! They don't even need a mirror to show you how much of a joke you are. It's you, dumbass!