1. Prepare a package of lime or apple Jell-O as directed and divide among 8-ounce mason jars or clear bowls, filling only halfway; refrigerate them until firm.
2. Prepare another Jell-O flavor, such as cherry, berry-blue or grape. While Jell-O is cooking, place three gummy worms on top of set gelatin and let another hang over the lip. Pour second flavor over the worms, filling to the top; refrigerate.