d-machine
A person who thinks they're the best at everything, but they're really just bad at life.
My teacher is a d-machine. She thinks she's the best at everything, but she still can't do long division.
My dad is a d-machine. He tried to fix the TV and now it's broken forever.
My friend's cousin is a d-machine. He tried to be a rock star and now he just sings in the shower.
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