Erik Adkins created this cocktail at the Slanted Door in San Francisco. It looks like a mix of a Hemingway Daiquiri and the Last Word: Simply put, the gin replaces rum in the former, or the grapefruit replaces the green Chartreuse in the Last Word Cocktail. There are slight adjustments to the proportions too. 

The bright flavors of this drink are delicious! It works both as a break from the sweetness in desserts and with a light meal or simply by itself. This may explain why it has been on the restaurant's list for many years. It's particularly delicious in winter when grapefruit is at its peak. It would help if you used yellow grapefruit, but pink also works. The higher acidity in the yellow grapefruit will help balance the sweetness of the maraschino better.