It is the "Final" post, and or entry a person makes before they delete their account. The user is normally back within a week because they are to addicted to the site
Person1: This is my Death Post, I am deleting this account...
Person2: Hey that is sad, I hope you have a good life
Person1: **Deletes account**
Person3: Hey person2, remember person1?
Person3: Im person1, couldnt stop my addiction