Fill a cocktail glass with ice, a dash of water, and set aside to chill.

Combine 30ml Gin, 30ml Cointreau (I'm sure any orange triple sec would be fine, though), 45ml Ruby Red Grapfruit juice (or similar red/pink grapefruit juice, but NOT the regular yellow stuff, which is far too bitter for this cocktail), and 20ml Pineapple Juice into a shaker, and shake.

Remove ice from cocktail glass, and strain drink into glass. Run a (small) slice of lime around the rim of the glass, squeeze a bit into the drink, and drop the lime into it.

Drink.