Prepare the cake according to the instructions on the box.
In a bowl, combine six ounces of frozen coconut, one cup of sugar, and eight ounces of sour cream to create a filling for the layers.
Bake the yellow cake mixes, using both boxes to create four layers.
Once the cakes are baked, layer them and spread the coconut mixture between each layer.
To make the seven-minute frosting, set up a double boiler and combine two egg whites, one and a half cups of sugar, two teaspoons of Karo syrup, one third of a cup of water, and a dash of salt in a bowl.
Beat the frosting ingredients for one minute, then place the bowl over the double boiler and cook for seven minutes, beating continuously until soft peaks form.
After seven minutes, remove the bowl from heat and stir in one teaspoon of vanilla, then continue beating until stiff peaks form.
Use the frosting to decorate the cake and sprinkle with colored coconut to create a bird's nest effect.
