Mix flour, Old Bay, salt & pepper in a medium bowl. Whisk in 8 oz (1 cup) of the beer. Batter varies by atmospheric conditions, so you may need more beer to thin batter to the consistency of a slightly thick pancake batter. Let batter stand for 15 minutes. Thin batter if necessary using additional beer.
Heat about 1-2 inches/2.5-5 cm oil in a deep large skillet to 350F/180C. You could also use a deep-fat fryer if you have one. This recipe is NOT recommended for air fryers.
Dry shrimp thoroughly. Dust lightly with flour.
Dip shrimp in batter and carefully add to hot oil—do not crowd the pan!!!
Fry 2 minutes then turn and fry an additional 2 minutes. Remove to a paper towel lined plate and keep warm in a 200F/100C oven while frying additional batches.