Warum brennt nach KFC der Arsch?

The reason is that
similar nerve endings exist in mouth and anus. Sharp dishes, especially chili, therefore not only burn on the oral mucosa, but also usually again at the end of the anus. Special receptors are found in both mucous membranes.

Come on
capsaicin the fabric,
who makes the sharpness in the chilischote, adapts its structure exactly to the receptor and this reacts. In addition to the perception “sharf”, this sensor can also feel temperatures which then trigger the intestinal movement, blood circulation and the production of mucus and secretion and convey the unloved chili to the outside more quickly.

https://www.thieme.de/de/sonder Labels/po-fakten-zum-schmunzeln-154747.htm#:~:text=The%20bas%20ist%2C%20dass,Schleimh%C3%A4uten%20find%20sich%20spezielle%20receptors.