I've got a related joke. A mathematician walks into the room looking distraught. His wife asks him what's wrong, and he says he's worried their child has a lea

I've got a related joke. A mathematician walks into the room looking distraught. His wife asks him what's wrong, and he says he's worried their child has a learning disorder. She asks why. He says he was trying to teach their child how to add, but he couldn't even understand zermelo-frankael set theory, so there was no way he'd learn how to add numbers before kindergarten.