Add a good-sized handful of ice to a 24-ounce "big girl" beer glass. Add 8 ounces of the lemonade to the glass. Slowly, carefully, add the bottle of beer to the glass (go too fast and it's a mess). Add the vodka, then top it off with the last ounce of lemonade. Stir once, with a mighty long spoon. Squeeze the lemon slice over the top and drop it in.