Just another horse joke A donkey walks up to a horse exclaiming ""good news, the doctor called and it's going to be a boy!"" The horse mumbles under its breath ""I really wish you hadn't made an ass of yourself."" The donkey retorts by stating ""well.. due to speciation it'll be a mule and, as such, it will be infertile, dying childless and alone. You knew this going in, Martha!""