A walking erection
That guy’s brain only works when his cock is hard. So he’s basically a walking hard-on with a brain made of stupid.
I asked him why he didn’t finish his math homework. He said, 'I was too busy thinking about my cock.'
He walked into class and said, 'Today’s lesson is about hard-ons and math. Pick one.'
His teacher said, 'You’re not paying attention.' He said, 'I’m paying attention to my cock.'