Fill a stockpot two-thirds full of tap water. Add lemons, salt and shrimp boil. Cover and bring to a full rolling boil.
Add shrimp, cover and remove from heat. Let sit for 10 minutes.
If using frozen shrimp: Add first three ingredients and bring to a boil. Add frozen shrimp, cover and bring back up to a boil before removing from heat. Let sit for 10 minutes.
Drain and serve hot or cold with cocktail sauce or Alabama White Sauce.