Commercial for DogFood

Show a large breed dog bending over with a smaller dog standing on his back, then an even smaller dog with a chihuaha on the top (like a pyramid of dogs). The chihuaha leans over the counter at the Pet Store asking for the brand of dogfood. The checkout girl's expression is she can't believe how tall the chihuaha is as she cant see the other dogs behind the counter. The chihuaha just smiles nervously, flexing his muscles: I work out.