In a cocktail shaker combine rum, grapefruit juice, simple syrup, orange liqueur, lime juice, pecan liqueur, and grenadine. Fill with ice cubes. Cover, and shake vigorously to combine.
Fill a chilled rocks glass with crushed ice.
Strain rum mixture into prepared glass. Garnish with grapefruit, if desired.
Notes
*We used Cointreau and Evangeline's Praline Pecan Liqueur.
Recipe by Taste of the South at https://www.tasteofthesouthmagazine.com/grapefruit-pecan-punch/