"Why fucking A, Peace? Why not fucking B or C?"

well, as matter of fact, it is none of the above!

The expression was origionally "Fuckin' AYE!" as in YES!, RIGHT!.....but someone (or a number of 'someones') saw it in print, and had no idea how to pronounce "aye" and so said "A" verbally.....and off we went, with no one knowing quite why A was used instead of B....

do a Google search and you'll find MANY examples of AYE and a few explanations. (I first heard it in 1970, in a warehouse as "AYE" and was bewildered when 20 years later, I started hearing "A".

(no...you don't need to tell me "the language evolves", I know that....it evolves even more when people don't stop to ask themselves what they are saying!)