Special equipment: 16 to 32 shot glasses
Place the shrimp and 5 cups cold water in a medium saucepan over medium high heat and bring to a boil. Remove from the heat. Drain the shrimp and pour cold water and ice cubes over them to chill.
Place the ketchup, chili sauce, horseradish, celery and lemon juice in a medium bowl and stir to combine.
Line up 16 shot glasses. Add a spoonful of cocktail sauce to each glass. Place a shrimp in each glass with the tail sticking out the top. Garnish with the chives and/or parsley.