SFM Poster: Weapon Showcase 'Sydney Sleeper'

Whenever I see a Sniper use Sleeper, and they kill me with it, everone on the server excluding me shouts SYDNER SLEEPER RAGE. How the heck is it a rage wep? xD Machina is the more suitable Rage wep for Sniper (I use it a lot though, so I try to be decent and Headshot. I keep it for the Overheal killing X3)