The name given, by players of the game CoD4, to the assault rifle mounted grenade launcher do to the fact that it is seen as requiring little skill to use and the fact that it is, in fact, a tube.

Also, the use of said grenade launcher.

This refers to a derogatory word used for an online gamer in, xbox 360 and ps3, in two different games. The word noobtuber is often used while playing call of duty 4 live, when a player uses grenade launcher attachments on all of their weapons in order to get cheap kills. They usually cannot get kills any other way. It also refers to halo 3 or halo 2 live, when a player uses a rocket launcher and/or a missle pod, and repeatedly uses it as it keeps spawning.

A gaming action used in online shooters (i.e. COD MW2, etc..) involving the use of a rifle mounted grenade launcher to achieve easy kills.

A grenade launcher mounted underneath a gun, most commonly an assault rifle, in Call of Duty games. The word "Noobtube" comes from the player using it being a "noob" and the fact that the grenade launcher looks like a tube; hence the word Noobtube. Noobtubes carry 2 grenades that can also be refilled using the Scavenger perk or the highly despised One Man Army perk. They have a very large blast radius and enormous damage, leading to one hit kills even if the grenade lands 10-15 from the enemy. The most hated thing you can do with the Noobtube, is to join a domination game and shoot the Noobtube across the map at the beginning of the game into the enemies flag closest to their spawn, earning a 2-6 hit kill with one shot. The players using the Noobtube are called Noobtubers and are hated by many players in the gaming community because of the weapon requiring little effort to get kills with because of its high damage and blast radius. A Noobtubers K/D is usually quite high and they commonly achieve higher ranked killstreaks, (Pave low, Chopper gunner, AC-130, ect).

When some fagg on Cod uses a greanade launcher and kills you

Person who uses a grenade launcher in the call of duty series who sucks balls

Any grenade launcher attachment used in Call of Duty Modern Warfare, employed by n00bs of the highest caliber.

Most popular in games like Halo or CoD, noobtubbing is the act of overly using of the Brute Shot or Barrel-mounted grenade launcher, respectively.

Doing this, more often than not, makes other players dislike you, avoid you, or call you a noob.

The nickname of the the Halo or Halo II rocket launcher when used "noobily" by a noob that hogs the rocket launcher(the most powerful weapon in the game) and tends to "camp" but ultimately loses the battle and/or all his dignity and reputation.