Potatoists worship the holy moon baby and the small potatoes. They believe that the Meme Army protects them from the wretched Vegital who lives in the Chewy Boba land.
If a Potatoist lives a good life, they are judged and sent to the basket, a holy land ruled by potatoes. If they are bad, their souls are sent to the Vegital's Realm and their Potato is sent to McDonalds.
A potatis is a swedish word, meaning that you are completely useless. Originally the word translated to potatoe in English, but that meaning has been lost.
You are such a potatis, failing to throw a granade properly without killing your friends.