John Lennon watched a lot of TV. He wrote this after hearing "Good Morning, Good Morning" in an ad for Corn Flakes.
The animal sounds were dubbed in from a sound effects disc. They were arranged in order of creatures capable of eating the one before, at Lennon's request.
George Martin edited the chicken at the end to go right into the guitar of the Sgt. Pepper reprise. One of the innovations of the album was the songs blending together.
Lennon: "It's a throwaway, a piece of garbage."
The lyrics, "it's time for tea and Meet the Wife" refer to the BBC sitcom Meet The Wife, starring Freddie Frinton and Thora Hird. (thanks, Dan - Indianapolis, IN)