The Big Fucking Gun (or more politely, Big Freaking/Fragging Gun) found officially in all of the high-profile id Software games like Doom and Quake. Fires a very large green ball of man-made lightning and then upon impact, the weapon instantly releases a huge spread of energy to anyone that the BFG'er is facing. (Despite how extensive this definition is, it is loose.) In Quake II, the ball of energy will shoot lasers a certain distance for some additional pain.
Newbies hate the weapon, but some veterans consider the BFG a thinking man's weapon (in deathmatch)because of its strange behavior, slow firing rate, and high energy drain.

Stands for 'Big Fucking Gun'. A powerful weapon in the Doom and Quake series.

the BFG9000 was the most powerful weapon in the doom video games. it originally stood for "Big Fucking Gun" as explained in the game's design document. the quake games pay tribute to the gun with the BFG10k. in the recent doom motion picture, the gun is denominised on a computer screen as "Bio Force Gun".

Kids: Big Friendly Giant

Teens and up: Big Fucking Gun, from Doom series

big fucking gun such as in DooM and Quake, and some various mods for other games.

Sucks in Quake 3

Kids: Big Friendly Giant
Teens and Over: Big Fucking Gun
Tall Gingers: Big Friendly Ginger

Big Fucking Gun. A POWERFUL munitions device seen mainly in Hollywood action and science-fiction movies, first sighted in possession of Colonial Marines in James Cameron's epic "Aliens" (1986); now seen in almost every dark-themed science-fiction or action film since. Dark, hulking, made of questionable metal alloys that do not exist yet. Fires: plasma, explosives, Big Fucking Bullets, anything it fucking well feels like.

Also seen in various anime films.

A popular user option in "Doom", and used vigorously in the feature film version of the game. Other names: Standard-Issue Big Gun, S.I.B.G., Big-Ass Gun, B.A.G., copwaster. For more details, visit Wikipedia entry "Aliens" (motion picture), and see paragraphs devoted to weapons created for and seen in the film.

Strongly desired by Daily Show host Jon Stewart, who during a "Doom"-related TDS interview with The Rock, claimed that he "got a hard-on" after temporarily gripping a B.F.G.; The Rock verified that Stewart indeed did get an erection after holding the weapon. Such is the power of the B.F.G.. If a B.F.G. can give Jon Stewart a hard-on, you would be wise not fuck with it.