I have a close friend who got let go and it was the boss who should have been fired instead.
When the boss called her on the phone my friend made sure to take the road of "dont pee on my leg and tell me its raining". She let her have it. She didn't hold anything back when it came to calling it how it is. (no name calling or anything though, just the facts)
I think my friend feels a lot better for having handled it this way. Though it makes you wonder, was it worth it, now that the boss will go and lie and ruin your reputation, etc.
Many people trying to build a career for themselves should probably not do this, it could backfire on your career.
I quit a place not too long ago. I didn't want to burn bridges so I didn't complain about the myriad of things I would have liked to complain about. But when they said "Well, we enjoyed working with you, it's been great", I simply could not bring myself to lie and reciprocate. It was an awkward minute or so while they figured out that I had just accidentally revealed that I hate their guts. It was awesome.