At this place:
Then here's the closest recipe I've ever had to the original at Pat O's:
1 (12 oz.) bottle of Grenadine
9 oz. light (silver) Rum
9 oz. dark (gold) Rum
9 oz. Orange Juice
9 oz. Pineapple Juice
3 oz. Triple Sec
3 oz. Lime Juice
Mix all the ingredients and serve over ice. Garnish with an orange and a maraschino cherry.
You don't need to use top-shelf rum, but don't skimp too much either. Caution: These are strong, but taste line fruit punch. A little goes a long way. One batch is enough for a gathering, and I suggest you serve them in small cups or glasses--not large hurricane glasses. That's too much unless you're stumbling down Bourbon Street.
Happy Mardi Gras!