The professor asked Johnny why he didn't support Sanders and he said it was because he was raised as a conservative. His dad was conservative. His mom was a conservative. So, he too became a conservative.
This frustrated the professor to no end so he went on the attack mode and asked Johnny that if his dad was an idiot and his mom was stupid, what would that make him? Not missing a beat, he replied: "A Bernie Sanders supporter." You've got to love Little Johnny!