The specific situation I was referring to was when I was working as a contractor on a rolling contract so I had very little legal protections, nor was I entitled to severance. I had been contracting there for years so this came completely out of the blue.

I've had a similar things happen a couple of other times though, once during a mass layoff of the engineering department and the another time at a startup that ran out of money after a failed funding round. Both of those times I was kind of aware of the situation about a month ahead of time and was in a better financial situation so they went much smoother although it was still a very stressful few weeks.

I've never been fired, but I've seen people get fired for fairly trivial reasons. Basically, "we don't really like him and this is a good excuse to get rid of him".