In a large pot, add water, parsley, thyme, bay, garlic, onion, lemon, grapefruit, peppercorns, salt and honey. Bring to a simmer for 5 minutes and remove from the heat. Add the ice and beer; this will help cool the brine solution. The temperature should be around 36°F/2°C to 38°F/3°C. Refrigerate the brine until it is well chilled (the brine can be made two days in advance). Use either a large 2-gallon container or 2-gallon Ziploc bag and add the Cornish game hen to the brine, then top off with the brine. Place in the refrigerator or in a clean cooler (with Ziploc bags of ice) for at least 12 hours. Remove the hens and dry well with paper towels. Let the hens sit at room temperature for about 45 minutes before using to help them cook more evenly.