Don't follow this jokers advice. Have seen this done, and it's not the way to go.
Keep massaging the crop with the bird upside down, and spoon feed a tea spoon of olive oil (Gently) down the birds throat.
Or warn water they don't like it but they can die unless cleared, a vet will cut the crop and stitch it and stitch you up for £ or so.
A blockage is often caused by long bits of grass so never feed grass clippings.