"without preparation," 1910; narrower sense of "withdrawal from an addictive substance" (originally heroin) first recorded 1921. Cold turkey is a food that requires little preparation, so "to quit like cold turkey" is to do so suddenly and without preparation. Cf. cold shoulder.
To “go cold turkey” is to withdraw suddenly and completely from an addictive substance or some other form of dependency: “Many people who attempt to quit smoking do so by going cold turkey rather than by gradually cutting down.”
Requiring abrupt and complete deprivation: They tried the cold-turkey cure (1921+)
Basic; unadorned; hard-core: Stalin didn't like certain cold-turkey facts Kennan reported (1920s+)