pebbles in your shoe

OK, so here's something I don't understand.

How do pebbles get in your shoes?

One of the major questions about the Meaning of the Universe in my book.

I always get pebbles in my shoes when I walk the dog on the Canal. Now, you need to know this, I wear sneakers that are a half size too big (I like loose shoes) and I tie them so I can take them off and put them on without untying them (I really, really like loose shoes).

There is a cinder path beside the paved part of the Canal--on the right, across from the water itself. So, I've always thought I got pebbles in my shoes from the cinder path.

But today, as an experiment, I only walked on the pavement or on the grass near the water and I had to stop 3 times to shake pebbles out of my shoes.

What is the physics about that? How does it happen? Is it just me or do other people have that same experience? Am I cursed? Do my feet expel pebbles from inside my soles somehow? What the hell is going on about getting pebbles in my shoes?

Any explanations anyone out there has?

I think if I stayed indoors I would eventually get a pebble in my shoe.

Am I being paranoid and crazy?

Where do those pebbles come from and how do they get in my shoes?

And should I call the pebbles "Dare". (An allusion for Godspell fans....)