On Da Book

a prepositional phrase used to describe time spent on Facebook. Used to replace saying "on Facebook", often said after making a stalkerish reference to something seen on Facebook.

"I was lurkin' on da book last night and found a picture of my ex making out with a fish."

Girl 1: I wonder if that guy from Chem is available...
Girl 2: He is. He just broke up with Sherry who is in nursing school.
Girl 1: How do you know that...?
Girl 2: What? It was on da book.