Ingredinet:
2 tbsp grapefruit juice (1 oz)
1 tsp simple syrup
6 tbsp light rum (3 oz)
1/4 cup lime juice (2 oz)
Ice cubes or crushed ice
1 lime slice

Method:
In highball or glass over ice, mix rum, lime juice, grapefruit juice and simple syrup.

Garnish with lime slice.