Like any person "running around like a chicken with its head cut off" a headless chicken does, indeed, run around crazily and without much thought—at first. But if that chicken is Miracle Mike, a chicken that actually spent 18 months without a head, the phrase takes on a new meaning.
To be a chicken with its head cut off, if that chicken is Mike the headless chicken, is to embark on a national tour and to be profiled in Time magazine. It is to spend your days drinking a milk-water mix dropped down your exposed throat from an eyedropper. And it is to die, when that eyedropper is accidentially left behind, a relatively calm death, in a motel room.
But let's begin with Mike's decapitation. In 1945, a Mrs. L.A. Olson, (wife of farmer Lloyd Olsen, says Time), chopped the head off a chicken. The blow was aimed with the intent of keeping as much of the neck intact as possible, says Bec Crew for Scientific American. (The neck meat was to be a treat for a visiting mother.) Olsen whiffed her blow and separated some, but not all, of the chicken's brain from its body.
Chicken's brains are arranged at such an angle that the most basic parts of the brain, the cerebellum and the brain stem, can remain nestled in the neck even if most of the head is gone, says Rebecca Katzman for Modern Farmer.
The day after Mike's supposed execution, says Ester Inglis-Arkell for io9, Mrs. Olsen found the chicken “sleeping with the other chickens, his neck tucked under his wing.”
Either his owners knew they had something big, or they just felt sorry for him. Either way, they took care of him and fed him with an eye dropper. Word spread about The Headless Wonder Chicken and people paid a quarter to see the marvel.
Soon, Mike's fame spread further, and he died in 1947 while he was on national tour. Occasionally, fluid would gather in his throat and need to be cleared; his owners had lost the tool they usually used to do the job. Mike choked to death on his own spit—and was finally still.