But it's not always easy to pull off, as this Counter-Strike: Global Offensive player finds out. He looks to be basically on the camera-focused player's shoulders, so close to getting that glorious knife kill.
Unfortunately for the knifer, YouTube user (and victim) Rustsandstuffs manages to turn around just in time to spray-and-pray the hell out of him before he can make the knife swipe. His terrified wails as a result to the close call are hilarious, and even more hilarious in the proceeding slow-motion version.
Knife surprise! [Reddit]