Dip the rim of an 8-ounce martini glass into the cream of coconut, rotating until the entire rim is coated. Press the coated rim into flaked coconut and rotate, again, until covered.
Add 2 maraschino cherries to the bottom of the glass, if liked.
Fill a cocktail shaker about halfway with ice. Add cranberry juice, coconut rum, sweet and sour mix, grenadine, and lemon juice. Shake to combine until the shaker feels ice cold (10 to 20 seconds).
Pour over maraschino cherries into rimmed martini glass.
Notes
Chill the glass: A frosty glass keeps the texture crisp and the rim set. Dry the rim: Pat the outside of the glass before rimming so coconut sticks only on top. Use fresh citrus: Bottled mixes are fine, but fresh lemon tastes brighter. Hard shake: Shake with conviction for proper dilution and a silky finish.