At my last job, the owner sent an email to an employee detailing his complaints with their performance. The employee got angry and sent his girlfriend a copy of the email with his reply of what an @ss his boss is and how clueless he is about everything.
The email was also sent back to the owner.
The owner showed me the email and we had a good laugh. The employee had received the email in the final stages of documenting his poor performance and was let go shortly after all this.