Defrost strawberries. Strain and reserve juice. Strain pineapple, reserve juice. Mash bananas.
Combine strawberries and pineapple. In a separate bowl, combine gelatin and jello with reserved juices. Add fruit and boiling water. Pour half the mixture in an 8x11 dish, and chill until firm.
Once the mixture has chilled, evenly spread sour cream over the top. Pour the remaining mixture over the layer of sour cream, and chill.