The burning sensation you get in your anus the day after eating way too much spicy food.

sphincter grease /ˈsfɪŋktər - grees (n.):

1. The resulting oily residue as having been rendered from an abnormally abundant and unkempt conglomeration of "swass" (aka. ass sweat).

-This advanced state of natural anal lubricant can typically be found on most hippies, destination vacation attendees, and hobos, and is commonly noted as the 2nd natural state of anal condensation, the first being "swass" and the 3rd being "ass butter." Sublimation is possible in extreme cases, however highly unlikely as sphincter grease plays an integral role in springboarding swass into a semi petrolic, pre-gelatinous state necessary for the achievement of ass butter.

The almost magic-like phenomenon when someone who needs to take a really bad poop gets within 20 feet of a toilet and immediately they have an almost uncontrollable urge to crap.

Someone who likes getting pounded in the butt.

A tight ass.
a) resulting from being in a tense or pressured situation
b) being uptight or generally harsh

having one's head up their ass

adj: a polite way of saying asshole