In a large pot, bring 5 cups water to a boil. Add a large pinch of salt and stir in the grits. Simmer until the grits are fully cooked, about 5 minutes. Remove from the heat and stir in the mayonnaise. (Reserve 1 cups grits for another use, such as Round 2 Recipe Silver Dollar Corn Fritters.)
In a saucepan over medium heat, cook the bacon until crispy, about 5 minutes. Turn the heat to medium-high, add the onions and cook until they begin to soften, about 3 minutes. Add the shrimp, sprinkle with salt and pepper and cook until shrimp turn pink, 3 to 4 minutes. Stir in the butter, lemon juice and hot sauce. Toss to coat the shrimp, and remove from the heat. Stir in the parsley.
Divide the grits among 4 bowls and serve the shrimp spooned over top of each.