Well Lepus Rex if I was an aneamic weakling who had my lunch tray deliberately knocked out of my hands by somebody who was much bigger than me I probably wouldn't say much at that moment either. The jock is a bully using his physical size and strength to intimidate smaller people. Why would I want to get hurt by opening my mouth when I can get my revenge with the pen a little later? Its a similar reasoning to what the jock uses when he atttacks people smaller than himself.