The BFG 9000 is the seventh and most powerful weapon found in the video game
Doom. It is a single shot mass destruction device, capable of destroying nearly any
player or enemy in the vicinity with just one hit. The Quake video game also
features a similar weapon, the BFG 10K.

BFG stands for Big Fragging Gun, according to the Official Doom FAQ.
But the original design document, millions of gamers worldwide and in
the movie, actor The Rock refer to it by a somewhat pithier epithet.

The BFG is selected by pressing the 7 key on your keyboard. When you pull
the trigger, there is a pause as the weapon warms up. Then a large green ball
of plasma shoots from the barrel.

A direct hit causes between 100 and 800 points of damage. And anyone remotely
in the blast area will take a serious amount of damage for their trouble.

The BFG first appears in a secret area of the level called Pandemonium.
However, typing in the cheat code IDKFA would instantly give you access
to all weapons, including the BFG.

The best course of action to defend against weapon 7?

Stay out of its way or you can kiss your butt goodbye.