noun: a half-turn
The act of turning around and looking in an irritated way (possibly with rolling your eyes) to the person in the seat behind you, as a result of his noise-making.
Asshole #1: shushh!
Me: dude, did that guy just shush me?
*Asshole #2 half-turns*
Me: Oh man, that guy just half-turned me, let's be quiet now.