What is the sip stick a common accessory for when serving cocktails?

The sip stick is primarily used for stirring the drink when serving cocktails. This accessory helps to mix the ingredients evenly and can enhance the drink's flavor and presentation. The use of a sip stick ensures that the cocktail achieves the desired balance of flavors, particularly in mixed drinks where uniform consistency is crucial. While it may also serve as a stirring tool, its main function is to assist in the preparation of the cocktail by ensuring everything combines well. Other options such as garnishing, measuring, or chilling refer to different aspects of cocktail preparation and presentation that do not align with the primary function of a sip stick.