In a large pot, combine 4 cups water with the sugar. Heat over high heat for 3-5 minutes, stirring until the sugar has dissolved completely.

Remove from heat and add the cranberry juice, frozen lemonade (don't make it into juice, just add it frozen), and the orange juice.

Stir until the lemonade is dissolved.

Pour the juice into two 9x13 inch casserole dishes or cake pans. Or any wide shallow dish will do.

Cover and freeze until solid, at least 3 hours or up to 1 week.

Meanwhile, sugar the rims of the glasses. Pour colored sugar into a small bowl or a plate. (Any color would be fun, but I love to do red sugar. Plain white sugar would be pretty, or yellow. Green would be festive for Christmas!)

Rub the rim of the glasses with the lemon slice. Dip the glass into the sugar, then set aside to let dry. It's great if you can do this an hour or so before serving, but it's not necessary. You can even do it the night before your party to save time.

When ready to serve, use a fork to break up chunks of the slush and add to each glass.

Pour Cherry 7Up in each glass.

Garnish with fresh cranberries and an orange slice, if desired.