The Cobra's Fang is a vintage tiki cocktail invented by Donn Beach that calls for a mixture of Demerara 151 and Jamaican dark rum, along with fassionola and falernum syrups, orange and lime juice and a dash each of bitters and grenadine.
The recipe from the book Hawai'i: Tropical Rum Drinks & Cuisine By Don the Beaschcomber calls for it being garnished with fresh mint and a lime wheel, although a length of spiral cut lime peel made to look like a snake is used for aesthetics in some cobra named cocktails.