This is a fighting strategy routine originally developed for use in the
first person shooter game
Quake 2 - or more specifically, the
Action Quake 2 mod for said game. (See that link for further reference.) However, it is also compatible with games such as
Counterstrike, a mod for
Half-life.
The doctrine is dependant on getting a high-powered weapon, preferably a shotgun and most preferably a double-barreled, non-pump action shotgun, such as the sawed-off shotgun in Action Quake 2. Thereafter, one relies on stealth and hiding, and tries to get a close surprise shot on the unsuspecting victim, screaming "KABLAM" as the attack is executed.
This is why the sawed-off shotgun is preferred - the spirit of the strategy is to rely on one high-powered shot only. The long reloading time of the weapon further elevates the bragging potential for the person who follows the doctrine.
In a perfect setting, the doctrine is used while playing said games on a LAN. This way, the psychological effect of the "KABLAM" exclamation is maximized.