Ermmmm...I really dont know...good question!! I did look it up though.....
The etymology derives from the phrase talk turkey, in which someone deals matter-of-factly with a subject[1]. Some, however, believe the derivation is from the comparison of a cold turkey carcass and the state of a withdrawing addict � most notably, the cold sweats and goose bumps. It is often preceded by the verb "to go," as in "going cold turkey."
I was always under the impression that it was connected to the pimpling of a 'cold turkey' carcass, and similar physical effects in the withdrawing addict.