Using the lime, run it around the rim of the glass. Then dip the rim of the glass into coarse salt.
Carefully add ice to the glass. Pour the margarita mix, tequila, and triple sec into the glass. Mix well with a stirrer. Your glass will be half full. Carefully, turn the Corona Extra upside down in the glass. Beer will begin to pour out and will eventually stop flowing out. Garnish with the lime and enjoy immediately.