Ingredients:

12 ounces frozen limeade concentrate (do not thaw)
4 ounces grand marnier (or other orange flavored liqueur)
12 ounces cuervo tequila, gold 1800 (i have also used cazadores with good results)
8 ounces water
12 ounces light beer (i like corona)
1 lime, cut into wedges

Method:

Pour limeade, Grand Marnier, tequila, water, and beer into a large pitcher.
Stir until well-blended and limeade has melted.
Add plenty of ice.
Pour into margarita glasses rimmed with salt (if salt is desired).
Garnish with lime wedges.