Civet coffee, also called Kopi Luwak, is the world's most expensive coffee. It is produced from coffee beans that are partially digested by the Indonesian palm civet and then excreted.
In Vietnam, weasels eat coffee berries and puke the undigested seeds. These are collected and roasted into beans. The stomach acids rid the beans of bitterness-inducing compounds.
The rhesus monkey and Formosan rock macaques who help process the beans of this coffee don't actually digest them. They chew them and spit them out. This coffee comes with tooth marks.
Certain mushrooms like chaga, reishi, lion's mane, and cordyceps are dried, ground up, and added to regular coffee. It can be consumed by caffeine-sensitive people.
Bulletproof coffee is consumed with butter infused in it. Black coffee is poured over a base of condensed milk and then topped with oodles of melted butter.