Combine mango, pineapple, and chili pepper. Toss in the lime juice, cointreau or orange juice, the sugar or agave nectar, and some of the reserved mango juice if you used canned mango. Let this mixture sit, chilled, for at least 30 minutes before serving.
To serve, spoon fruit into sherbet glasses. Pour the juices over, and top with the flaked coconut. Serve immediately.