Place the shrimp in a medium bowl and season with salt and pepper.

In a separate bowl, whisk together the flour, 1-1/2 tablespoons salt, 1 tablespoon pepper, and the cayenne; dip a finger in and taste, and adjust seasoning to suit you. Heat oil to 350°F in a large pot or deep fryer. Pour the buttermilk mixture over the shrimp and toss to coat. Working in batches, toss them in the seasoned flour and slip the battered shrimp into the hot oil; fry until golden and crisp, about 5 minutes.

Drain on paper towels.
Serve them straight up with cocktail sauce or load them onto slabs of French bread for po' boys.