Yesterday I woke up and realized that this is the worst career experience I've ever had. Therefore, I'm officially notifying you of my resignation from [company name]. My last day will be today.
This company has many problems. [insert problems here]
On top of that, I can't stand to work for you any longer. You, alone, have been a constant source of pain and suffering for me ever since I started this job. I can't understand how you made it this far in the professional community.
Today is a great day for me. I will never have to see, hear or listen to you ever again. Goodbye, and good-riddance!