Smile for revenge
The first time I was made redundant I was furious, as we'd just turned our first profit, been reassured by our boss and I'd just cancelled my mortgage insurance the previous day. We were being called in one at a time and I told my fellow sacked workers I'd give the boss hell when it was my turn. An older, wiser colleague told me, "Nah, go in and smile sadly, tell him what a pleasure it was to work for him and how much you wish him well. That way he'll feel far, far worse."