Mostly known in the game "Call of Duty: Modern Warfare 2". This is acquired by getting a 25 Killstreak (25 kills without dieing) on the online multiplayer game modes. When you activate this, there will be a ten second countdown until the match ends and your team automatically wins. This killstreak is basically what made Modern Warfare 2 a camp-fest and surprisingly all shitty players have it on as a killstreak but never get it....
User 1: Omg I am so getting a Tactical Nuke this game!
User 2: Nah you will probably camp to get it you douche nozzle!
User: 1 Stuff you I am a legit noob asshole!