Timmy makes a wish, 'I wish to be the best in town' but Cosmo makes the mistake of hearing 'Best' as 'Beast' and now Timmy turned into a Cat/Dog Alpha that gives off a scent that drives every Female Cat/Dog that is in town crazy to mate with him.
Maybe even have him get turned on by the scent of woman and try to fuck them which works once they get a wiff of his own scent.
