I have painful memories of walking barefoot through what appeared to be a field of soft grass. Some of the grass had produced sharp pointed fruit. While the spikes on some of the fresh burr fruit were not as stiff, they still were able to penetrate the tough skin on my feet. As the fruit dried, it turned brown and the spikes hardened. More painful.
No! This experience did not encourage me to wear my shoes. Instead, I learned to recognize grass that produced burrs. For more photos of burr fruit producing grass, see Burr Fruit.
The spiked grass fruit sticks to things other than skin, including clothes and animal fur, and is carried to other areas. How seeds are dispersed is an interesting study. Some seeds can actually move around all by themselves, such as a grass called Thread-and-Needle. When you see the seed you will understand this name. For more information about this grass, see SEED DISPERSAL:MECHANICAL MOTION