How to send back defective Nike shoes

So, once upon a time (read: high school) a buddy of mine told me that you could send back defective shoes. Shocked and elated, I rode that train until I managed to forget about it at some point in college.

I bought a pair of Nike Hyperdunks in September 2008 and one of the Zoom Air bags has deflated and I wanted to know how to send them back. By the way, these have to be some of the most comfortable shoes I've ever owned, especially for walking around NYC.

Here's how. There's no catch other than the shoes have to be less than two years old and actually defective.