For fun.
Make a grass whistle.
1. Take a grass which is longer than 5 cm in length or simply take a grass longer than your thumb.
2. Make sure that the grass is wide, about 0.5 to 0.7 cm.
3. Narrow grass might be difficult to handle.
4. Put your thumbs together in a manner that your thumbs nails are towards your face.
5. Hold the one end of grass between your thumbs and let the other end hand downwards.
6. Now fold your palms in a manner that it looks like a cup (one palm over the other).
7. The cup should be tight.
8. Make sure you can only see the edge through the narrow opening in your palms.
9. Now blow gently through that opening.
10. You can feel the grass vibrating and a whistling sound. Your whistle is ready.