In "Team Fortress 2", what is the fastest taunt kill that can be pulled off?

In Team Fortress 2, the fastest taunt kill that can be pulled off is with the Showdown taunt. This taunt, available for the Spy class, allows the player to instantly kill an enemy upon successful completion. Unlike other taunts that require a few seconds to execute, the Showdown taunt eliminates any windup or delay, resulting in an immediate kill. Therefore, it is considered the fastest taunt kill in the game, enabling players to eliminate unsuspecting enemies in an instant and potentially turn the tide of battle.