The slang word "nooblauncher" is often often pinned to players that repeatedly fire a rocket launcher, RPG, or similar rocket firing device as a method to earn a kill as their first offensive action.
Like noobtubing, an RPG in Call of Duty (for example) is almost always a one-hit kill, requiring no skill other than aiming the weapon and then firing it when the target shows up on the screen.
A player is only considered a "nooblauncher" if he starts using rocket firing weapons as a method to kill just the players that are on foot, instead of vehicles such as helicopters and tanks as well.
Man, that guy only ever killed me with that darn Rocket Launcher!
Yeah... What a nooblauncher...