We read about this online and tried it, and it DOES work! Our disposable razors have lasted 3-5 times longer than normal by running them along an old pair of jeans. What a simple way to cut down on razors (less waste, and saves money!). My husband gets about a month out of his (versus a few shaves), and I don't even remember the last time I replaced mine!
Run the blade the opposite way you'd shave along the jean material about 10 times (you don't need to press hard)
Then turn it around and run it back the other way another 10 times.
You can see other tips for making your razors last longer on this article I posted as well on WikiHow!