Summarize this article in one sentence.
Pick 1 cup red or green seedless grapes off the vine. Wash the grapes and pat dry. Carefully slice each grape in half. Set the sliced grapes to the side. With a can opener, open the cans of pineapple, mandarin oranges, and maraschino cherries. Empty the contents of the cans into a large colander. Drain the fruit very well. If you could not find halved maraschino cherries,  slice the cherries in half now. Scoop one 8 oz container of whipped topping into a medium sized mixing bowl. Add 1 cup sour cream to the bowl. With a spoon, combine the sour cream and whipped topping. If you are using a frozen whipped topping, thaw before combining it with the sour cream. Add 1 ½ cups sweetened coconut flakes and 1 ½ cups mini marshmallows to the sour cream-whipped topping dressing. Carefully fold the coconut and mini marshmallows into the dressing. Add the drained fruit and nuts (optional) to the bowl. With a spoon, fold the fruit into the dressing. Cover the fruit salad with a lid. Place the covered bowl into the fridge for 1 hour. Once chilled, remove from the fridge and serve. If your mixing bowl does not have a lid, you cover the dish with saran wrap or aluminum foil.

Summary:
Wash and slice the grapes. Drain the canned fruit. Combine the sour cream and whipped topping. Fold the ingredients into the dressing. Cover the ambrosia and chill before serving.