This is the original recipe for a drink that was created by a New Orleans bar owner, Pat O'Brien in the 1940's. His bar is in the French Quarter and you can buy a mix for this to which you would just add the rum.
In a cocktail shaker, mix rum, passion fruit juice and sugar until sugar is dissolved. Add grenadine and lime juice and stir to combine. Add ice cubes and shake. Strain into cocktail glass and garnish with orange and cherries.