What does f'ing A mean?

Supposedly the A is for awesome or affirmative. So it is usually just a way to say something is really good or you really agree with someone.

My job sucks
FnA right it does

I think I originally used to hear it as "F---- A affirmative," but it has been shortened over the years.

I found it annoying in the movie.
It was said too much.

It could be 'A' as in the first letter of the alphabet, you can't get better than an A rating; it means 'that's really great', either way.

You seriously have never heard anybody say, "fuckin' A" before?

That little phrase was big in the 80s, heck I don't remember this movie much so I don't remember them saying it of course. Honestly, I would have thought it came from surfer culture in California, it kinda sounds like it.

It was said a lot when I was a kid. Not said much anymore. They just dropped the A.