The shake technique is used to combine and chill three or more ingredients (with some exceptions), to be served with ice from the shaker. Pour the ingredients into a boston shaker with ice, shake vigorously for about ten seconds, open the shaker and pour the entire contents, including the ice, into the glass.
Check out the recipe for sicilia beach.
One more tip
When using the boston shaker, the large mixing tin should always be turned towards the customer in order to prevent splashing the customer in case the shaker is not properly closed.