In a large pot bring beer, water, lemon, celery, onion, and Old Bay to a boil.
Reduce heat and simmer until celery and onions are limp. 30 to 60 minutes.
Remove celery, onions, and lemon.
Bring the liquid back to a boil and add shrimp. Frozen shrimp is fine.
Boil just until shrimp floats.
Immediately turn off heat.
Add 2 cups of ice to shrimp and liquid.
Allow shrimp to steep in water for 15 to 30 minutes.
Remove shrimp from liquid and serve warm or refrigerate and serve cold. Sprinkle with additional Old Bay seasoning if desired. Serve with lemon wedges, cocktail sauce, and plenty of napkins.
Notes
Any size shrimp can be used, just cook until shrimp float. Time will vary by size of shrimp. Frozen shrimp should also just be cooked until they float.