In a bowl add the strawberries, blueberries, sugar, grenadine, and lime juice. Stir to dissolve as much sugar as possible. Cover and refrigerate for at least 1 hour, stirring a couple of times to agitate and help create juices.
When ready to serve, divide the mixture among 4 low ball glasses. Pour 6 ounces beer into each glass and give a gentle stir. Drink!