A group of 2 straight girls and a gay guy. They have a secret handshake, and they recognise other possible future members of the The Sisterhood by their correct demonstration of the "Bend and Snap" (As seen in the popular movie "Legally Blond").
The Sisterhood are extremely bitchy by nature, and will shun out all others.
Althouhg they usually travel as a pack, a solitary Sister will become irritable, mopey and even more anti-social than usual until they are united with another Sister, an which point they will immeadiately fuck off to whereabouts unknown (possibly a secret hide out).
Person 1: LMAO! Did you see what the Sisterhood just did!
Person 2: PMSL! Yes, yes I did. Ugh - Absolute cunts.