In large saucepan, heat rosemary, lemonade, beer, baking soda, salt, peppercorns and 2 cups water to a boil over medium-high heat; reduce heat to medium. Add shrimp; cook 2½ minutes or until internal temperature of shrimp reaches 145°, stirring occasionally. Drain shrimp mixture; transfer shrimp to large bowl filled with ice and cold water. Let shrimp stand 10 minutes; discard remaining solids. Makes about 24 shrimp.
In small bowl, whisk garlic, ketchup, lemon juice and horseradish. Makes about ½ cup.
Spread ice on serving plate. Arrange shrimp over ice; serve with sauce garnished with lemon wedges, if desired.