That one thing that schools do where nobody actually gets books, and everyone just gets a UV pen or something like that because usually all the books they have are shit.
Person 1: Hey dude what did you get at the book fair, I got an eraser that looks like a phone.
Person 2: Nice, I got a UV pen!
A portable bag worn on your back. You can store multiple things inside of it. There is no sexual definition. What were you expecting?
Guys, I just stole something from John's backpack!