Use a pint glass for this - nice and simple just add the Rum, Vodka and Lime juice cordial (equal amounts - 50cl) then top up the rest with Cola.

The reason for me giving it this name is simple, its a double decker of spirits. With Limeys (English people) on the bottom, and up top loads of American tourists!

Alternatively try it without the Cola for an extra sweet drink, however you have a regular London bus then!