to leave, to go away,to depart. In the trades (electricians, plumbers, iron workers, etc. used a union book for identification. When they would say :I'm going to "book out" and go to work on another job site.
Person #1: Shit he has a gun!!
Person #2: What!?! (sound of footsteps)
Person #1: Hey where did you go five minutes ago!?!
Person #2: Hell I booked it out!! I was gone!