The dead parrot sketch is one of the masterpieces of the Monty Python canon; it concerns a confrontation between a disgruntled customer (played by John Cleese) and a shopkeeper (played by Michael Palin), both of whom hold contradictory positions on the vital state of a parrot of the Norwegian Blue species. The customer alleges that the parrot is dead; the shopkeeper maintains that it is merely resting (and also 'pining for the fjords'). The customer, who has obviously swallowed Roget's Thesaurus for breakfast, goes on to point out that the parrot has 'gone to join the choir invisible', 'shuffled off this mortal coil', and furthermore has been nailed to the perch. All of the foregoing is systematically refuted by the shopkeeper.
Some critics have seen this as a sixth level theological argument concerning the existence (or otherwise) of God. Other critics haven't.