Livestock ** Bit rude (Mayor of the place to be)

A city boy moves to a new farm in he country and has decided that he wants some livestock. He sees a farmer and stops him requesting some animals for his place. He sees the farmer has a rooster so he asks if he could have it, the farmer stops him and states that i the country it is referred to as a cock. The farmer has a donkey and the city boy wants it, so the farmer agree to the sale, but he warns the city by that the donkey (referred to as an ass in the country), will sit unexpectedly and the only way to get him up is to scratch him behind the ear. So the city boy agrees to all of this takes his newly purchased "cock" and "ass" and starts walking home. Wouldn't you know it about half way there the Ass sits down, a lady drives by and asks if he could use a hand and he says "yes, please hold my cock while I scratch my ass"