Green’s Dictionary of Slang

cold turkey adj.

[SE/cold turkey n. (1)]
(US)

1. honest, candid.

Bismark Daily Trib. 23 Dec. 4/1: The Valley City Times-Record puts the gaff to Col. Bloom in this wise, which [...] is cold turkey talk.
[US]New Yorker 16 Sept. 19/3: Just cold-turkey business, you lousy faker! [DA].
[US]N.Y. Daily News 4 Oct. 9C: Stalin didn’t like certain cold-turkey facts Kennan reported about Russia [W&F].

2. of an idea or situation, impossible, beyond viability.

[US]‘Hugh McHugh’ You Should Worry cap. 1: In the meantime Bunch and I had passed away. ‘It's [i.e. a plan to take Tango lessons] cold turkey,’ I whispered.

3. unconscious, dead.

A. Baer Says ‘Bugs’ Baer 7 Sept. [synd. col.] [heading, of a defeated boxer] Miske Cold Turkey.
[UK]I. Fleming Diamonds Are Forever (1958) 132: Out, Limey, or your pal’s cold turkey.

4. emotionless.

[US]H. Miller Tropic of Capricorn (1964) 96: The haughty one with the statuesque figure is probably a cold turkey fuck.