Ingredients:

6 c water
3 c granulated sugar
2 12 oz. cans orange, frozen juice concentrate
1 cn pineapple juice,(46 oz.)
7 ripe bananas,(7 to 8)

Directions: 

Dissolve sugar in water. Set aside. In a blender, combine one banana, some orange juice concentrate, and sugar-water mixture. Blend until smooth and transfer into a very large mixing bowl or large pot. Repeat this step until all the bananas, orange juice concentrate, and sugar-water mixture are blended.

Add the pineapple juice to the banana-orange mixture. Stir until blended. At this point, you may freeze or refrigerate until ready to serve. When ready to serve, add equal amount of 7-Up to the banana-orange-pineapple mixture (50/50 ratio).

This is very attractive in a  punch bowl because there is a layer of foam on the top. Pureed strawberries or other pureed fresh fruits may be added to this punch.