There are shoes for children that squeak intentionally.
It is the worst thing ever.
I saw—excuse me, heard— a toddler with them on today and was seriously dumbfounded. I couldn't stop staring. The mom didn't even seem to notice the fact that it was bothering everyone but her.
I sort of feel like this is a bit of a public disturbance. I'm not interested in hearing your child every time she takes a step. This is especially true when you're letting her run around the entire front of the store.
I looked these shoes up when I got home and there are several different companies that make them. One company, Squeaky Shoe Store, explains the benefit of these shoes very well. The idea is that the position of the squeaker in the shoes encourages kids to walk correctly. (Of course, the main points on the website are things like the fact that they're so fun, etc., but this is the point that actually makes them seem useful to me.)
But the best part? The squeaky part comes out to allow for "quiet time!" You know when a great time to take the squeaky part out would be? WHEN YOU'RE IN A SHOPPING MALL. Or actually, anytime you're in public would be good.