It's a nickname for the Grenade Launcher used in all sorts of shooter games that makes the Multiplayer veterans of the genre cringe. Infamously derived from it's absurdly cheap kills and the blatant lack of skill needed to use it. It has existed in the FPS and TPS genre for a long time. While the weapon has been notoriously overpowered in many games for years, Many Developers fail to try and fix the problem at hand. With the general public's expectations of pretty explosions, 'Modern' weapons and essentially a pretty fireworks show, the 'Noob tube' unfortunately has always found itself a role, somewhere and somehow in almost every Shooter game, giving new players an overpowered 'noob-ish' weapon and giving Veterans of particular games a reason to break their controller (or keyboard).