Add dark rum, banana liqueur, orange juice, lime juice, and simple syrup.
Add 2 dashes of Angostura bitters.
Shake for about 15 seconds until well chilled.
Strain into a chilled rocks or highball glass filled with fresh ice.
Garnish with a banana slice or orange wheel and serve immediately.
Notes
Dark rum adds depth; substitute light rum for a lighter profile. Adjust tartness with extra lime juice or sweetness with a splash more simple syrup. Use fresh juices for best flavor and serve cold to avoid dilution.