Pens pencils down

The deafening phrase used in the torturous chambers of a math class. This phrase is said while banging on the desk with a ruler, preferably breaking it, simply for the satisfaction gained from your pain. There is no annoyance like this one, as this will happen at any sudden moment. There is no reason behind why it is said, or if it is for specific situations. However all I know is after experiencing this, you will see the world for what it truly is. Beware.

Class: *Completely silent*
Teacher: *suddenly banging ruler on desk* PENS PENCILS DOWN
Class: *sobbing* Ms please, we are doing nothing wrong...
*ruler shatters*
Teacher: PENS PENCILS DOWN
Class: *dies*