When a pool of sweat accumulates around the ass crack region. The most serious cases of this disorder are often evident through one's pants.
Chris: Wow Matt, you have horrible reservoir ass.
Matt: Hey, shutup.
Joe: Yeah Matt, your anus has reached its dew point.
Matt: Hey, shutup.
Joe: Yeah Matt, your anus has reached its dew point.
by P. Ness August 4, 2006