Question

Why do new shoes squeak?

Answer 1

In The Netherlands the answer would be: because you haven't payed them yet.

Explanation:

But the real cause is that the leather is dry. To become supple it needs a mixture of waxes and moist. The waxes come from your shoe polish, the moist from your feet.

If you bend anything that is dry (both ways) it will make sound, as different layers inside the structure will not move smoothly over one another, but in many little spurts. These create a sound.