Peter decides to grow a moustache, but then he's mistaken for a fireman (because they all have moustaches), so he lends a hand when a fire breaks out at a local fast food restaurant.

The owner gives him unlimited burgers as a "thank you" but he eats so many that he eventually has a stroke. When Peter recovers, he vows to expose the fast-food company and becomes friends with a genetically engineered cow (Montalban) he meets after infiltrating the McBurgertown warehouse

Source: thefutoncritic.com