Been there, all about Wolf Ass by the Venerable Scylla and others
been there, discussed more on Wolf Ass here
Oh and here’s a scholarly article about how consumption of capsaicin increases the pain of anal fissures. If you go to Google Scholar and enter "Capsaicin’ and ‘anus’ you will be AMAZED by the number of research papers published on this topic, i.e. about 2,470.