I am a mid career enginer, I was requested two references, one colleague and one manager, for my current job.
What is your reason for telling your manager to fuck off? Ego satisfaction for 5 min? What about thinking that if you tell him what went wrong, maybe they can improve, which may improve the work conditions of your ex colleagues? I find that more satisfying. I always try to raise my voice to improve my ex-colleagues conditions before I leave because I’m freer to speak up.