Rocks In My Sneakers

Lately I’ve been getting rocks in my sneakers. Right at the front of the foot where I put all my weight on. I’ve been wondering. How did the rocks get in there? I don’t have any holes in my sneakers. They don’t have those tiny air holes on the side either. They have to get in from the top of the sneaker around the ankle. How do they do that? Rocks don’t wait for a sneaker the come by then jump up and try to fall in. I could only think of one way. You’re walking. Your left foot hits the side of a rock causing it to fly up into the air. While this is happening, your right foot comes by at just the right time for the rock to fall between your sneaker an ankle, then working it’s way up to the front of the foot.
I know it’s a long shot. That’s why people don’t have rocks in they’re sneakers all the time.