galaxy brain
when you think someone is brilliant, but then they say something dumb and you’re like, "what the hell?" it’s smart and dumb all at once, like a bad breakup.
He said, "Galaxy brain," after I explained the Pythagorean theorem in three words.
She called me a galaxy brain for saying the sky is blue on a cloudy day.
He said, "Galaxy brain," after I did a math problem in my head while eating a sandwich.