A place of worship (Catholic, Jewish, Protestant, etc) that attracts an inordinate amount of good-looking, young professional types with a reputation as the place to go go to hook up for both spiritual and booty worship.
You're at an Ass Mass when the kneeling segments entail dozens of women simultaneously reaching back to pull down their shirts to hide tattoos, and pull up their low riders to cover their thongs
A woman with a tattoo on the small of her back, aka tramp stamp, signifying she is of a higher sexual experience, and also most likely under the use of drugs do to the hideousness of her face, and/or her body. Usually of a lower intelligence, and sometimes borderline retarded.
I was totally about to mack on some girl, when i saw the tattoo on the small of her back, and realized she was a major ass crackwhore.