The Blue Lagoon is the name of a cocktail. It was presumably named after the motion picture The Blue Lagoon or the book that inspired it. The main reason for the name is probably the tendency for bars to link drinks to current movies or famous people. The directions below are an extremely fancy Blue Lagoon. Many bars will use one shot of blue Curaçao, throw in some lemon bar mix, and call it a Blue Lagoon. Even bartenders with a certificate in mixology will consider the sugar to be optional.
Sugar the glass rim, shake vodka and rum with crushed ice, pour into the glass, add lemonade, then pour Blue Curacao down the inside of the glass for effect.
See also: List of cocktails