The Terrible Shotgun

 is a small gun that only appears in Fallout 3. It is a unique variant of the Combat Shotgun and has the highest base damage of all weapons in the Small Guns category.

It is in the possession of Smiling Jack in the Evergreen Mills bazaar and can be repaired with Combat Shotguns.

Obtaining the gun from Smiling Jack

 * You can kill him (no Karma effect).
 * You can get into a fight with him and just shoot it out of his hand and pick it up before he does. Leave and come back later and he will be neutral again.
 * You can pickpocket his ammo, leave the area, save & reload and re-enter the Bazaar. The gun will then be in his inventory and can be pickpocketed (possibly a glitch).