1) In school hallways, someone pushes your books to the ground, calling a "BOOK CHECK"
2) When you drop a book.
"Stephanie just gave Russell a Book Check!"
To knock the books out of someones hand in the school hallways causing all of their papers, books, and folders to fly onto the floor. This generally makes them embarassed as well as late for class. It is often used on Freshman by upperclassmen. It is best used with a decleration of "Welcome to high school, freshman!" though "Welcome to freshman, high school!" is also equally used.
Senior:*knocks books out of freshman's hands*
Freshman: Dude what the fuck!
Senior: Welcome to freshman, high school!
Junior down the hall: Haha, that bitch just got book checked!