Rufus.

Manny has moved to a new school, and it's not easy to fit in. After wishing he had more friends, Manny finds a mysterious collar and puts it on Rufus, the family dog. Suddenly, Rufus turns into a boy! Manny's not sure what to do, so he enrolls Rufus in school. When the other students notice Rufus's silly dog antics -- chasing squirrels, eating without utensils, asking for belly rubs, and catching a soccer ball with his mouth -- he immediately becomes the most popular kid around. Manny is jealous of his new best friend but eventually learns that a dog's loyalty to his owner always comes first.