Serving the Acapulco #2 'cold' means the cocktail should be chilled before serving, usually achieved by shaking it with ice. 'Shaken, not stirred' refers to the method of placing the ingredients in a shaker with ice cubes, then shaking vigorously before straining into a glass. This method cools the drink quickly and mixes the ingredients thoroughly, giving the cocktail a slightly aerated texture, especially important for incorporating the egg white.