Not your garden variety infected anal gland...
Claimed and proven today - gastroenterologists are very desensitized. Uninhibited in the words of our lecturer. I have certainly never seen so many pictures of diseased anal orifices; and all before lunch.
One of my classmates found this concluding the entry about Gas / Eructation, Flatulance on the online version of the Merck Manual at merck.com

"The following piece appeared in the Gastrointestinal section of past editions of The Merck Manual, and is being reprinted here because of reader demand.

Flatulence, which can cause great psychosocial distress, is unofficially described according to its salient characteristics: (1) the "slider" (crowded elevator type), which is released slowly and noiselessly, sometimes with devastating effect; (2) the open sphincter, or "pooh" type, which is said to be of higher temperature and more aromatic; (3) the staccato or drumbeat type, pleasantly passed in privacy; and (4) the "bark" type (described in a personal communication) is characterized by a sharp exclamatory eruption that effectively interrupts (and often concludes) conversation. Aromaticity is not a prominent feature. Rarely, this usually distressing symptom has been turned to advantage, as with a Frenchman referred to as "Le Petomane," who became affluent as an effluent performer who played tunes with the gas from his rectum on the Moulin Rouge stage."