Someone who explicitly uses the shotgun in a first person shooter, especially Call of Duty, where shot guns are often overpowered.
Even more true on small maps, where the spawn points are stupid and close together, allowing said SGF to run rampant shooting without even aiming and mow people down. Examples: U-turn, Rust, Get Away, Shipment etc.
Takes very little skill as it is a point and shoot weapon, and very powerful. It is not an illegal form of play, but is quite frowned upon and frustrating for opponents. 100% of people would agree however, that it is fun to do occasionally for the sheer madness and angst you will cause your enemies.
Random player attacks with Striker shotgun in Modern Warfare 3: BOOM BOOM BOOM BOOM BOOM BOOM
Enemy dies: "Freaking Shotgun Fag! This is so retarded!"
Random player: "Trolololololooo!"
Enemy: Rage Quits