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Bugs is "Experimental Rabbit #46" in the Eureka Hospital Experimental Laboratory, Paul Revere Foundation (which sports the slogan 'Hardly a man is now alive' in punning allusion to Longfellow's "Paul Revere's Ride"). Bugs lives a pampered life, oblivious to the fact that a scientist plans on switching his brain (or at least his personality, since no surgery is involved) with that of a chicken (said chicken bears no resemblance to McKimson-only character Foghorn Leghorn).
After giving Bugs an examination (including a joke when Bugs reads the microscopic "Allied Trades Consul" disclaimer on an eye chart when told to read the bottom line), the scientist brings him out to the operating theater, in front of an audience of fellow doctors. Bugs, of course, thinks he's been brought out to perform. He pulls out all the stops, singing, dancing, scatting (ala Danny Kaye), comedy routines (including his impression of Lionel Barrymore), and magic acts. Upon finishing each act, he looks around to see the unimpressed, stern-faced doctors in exactly the same frame position each time ("What a tough audience! It ain't like St. Joe[disambiguation needed]!"). The scientist attempts to retrieve Bugs but is pushed away. He strikes Bugs with a hammer while the rabbit is in the middle of a scat routine, but Bugs quickly revives and, having failed as the entertainment, becomes a vendor instead, selling hot dogs to the scientists, only to be hammered again. Learning the scientist's intentions ("A chicken? That's out, Doc! I don't wanna be no chicken!"), Bugs runs and a chase ensues.
Bugs hides in a closet, not noticing a skeleton in there, and comes out scared when he does see it. Then, when chased into the laboratory, he makes an explosive cocktail and threatens the scientist with it, saying: "One more step and I'll blow ya up! This contains manganese, phosphorus, nitrate, lactic acid and dextrose!" But the scientist dismisses the threat, saying that the ingredients Bugs mentioned are the formula for a chocolate malt (upon drinking the mixture Bugs realizes, "I'm a better scientist than I thought"). Then he hides near an oxygen tent disguised as a Boy Scout, leading the scientist in the wrong direction.
Finally, Bugs is rendered helpless with laughing gas and placed on the table, metallic mind-switching caps on him and the rather uninterested-looking chicken. But at the last minute, he switches the electrodes (though it is revealed at the end that Bugs cut the wire connecting to his electrode instead) and the scientist ends up clucking like a chicken, while the chicken (with the scientist's mind) states in plain English he hopes that the experiment can be reversed ("In our next experiment, we will reverse the procedure, I hope."). Bugs tells the audience: "Looks like Doc is a victim of fowl play!" and laughs.
The ABC version shortened the part near the end where Bugs, the doctor, and the chicken are hooked up to the machine to remove the part where all three of them get an electric shock.