This negative, sarcastic speech can be given for humor to coworkers when leaving a workplace.
Thank you all so much for gathering here to bid me farewell as I {reason for leaving}. I'm really going to miss your incredibly funny jokes, the way you really supported me during this transition, and, of course, your thoughtfulness when I asked you for recommendations. Really, stand-up job guys.
I must say I'll miss {list of negative experiences being left behind}. But most of all, I'm going to miss {hated coworker}. There really is no greater joy than being here among all of you people just one last time.
So, all I can really think to say is this: so long and thanks for all the fish. I'm really going to miss you guys.