A sexual act in which the "Librarian" puts their hands in a prayer position before inserting them into an orifice and opening their hands out, forming a book shape.
Guy 1: I took this girl home last night, and it all got weird when she asked me to do the Librarian.
Guy 2: Yeah, I heard she's a real bookworm.
A group sex session in which multiple partners practice the "Librarian" on one another.
Guy 1: Hey dude! Do you want to join my Book Club?
Guy 2: Sure, what are you reading this week?
Guy 1: Faust.
Guy 2: Oh boy!