A commonly made mixed drink on the island Seychelles. In a short glass combine 2-3 ice-cubes, five shots of high proof rum, and the minimum amount of coke.
Seychelles is an isolated island in the Indian ocean. At one time imported products such as coke were more expensive than rum. Mr. D'offay coined the term with various bartenders on the island.
Today the D'offay double serves as a way subtly request a very stiff drink without arousing suspicion of your alcoholic tendencies to your intermediate company.
The term has since spread to many European countries, where it is illegal for bartenders to serve quadruples or stronger. It used as code for a quintuple rum and coke, with the understanding you will tip the bartender generously.
My god this drink is strong, what is it? a triple? No, it's a D'offay double.