Similar to: Milk sisters
When three or more females living under the same roof have all had sexual intercourse with the same man. They are probably decently slutty
and may have made a sport out of landing the same guys as each other. This is thought of as a bonding experience, and will be discussed in detail at the man's expense.
Although it will be understood among the girls that none of them are special to him, because of the jealous nature of a female, it is a courtesy for the sexual acts to occur outside of the women's home. If not, that just makes it a brothel
Girl 1: Hey, I just got back from Molly's house. Did you know her and her roommates have all slept with Doug?
Girl 2: Yeah, I heard they were running a regular milk sorority over there.