Mikel told me that he made these cut-offs from an old pair of khakis. Whenever you want to do this make sure you wear your khakis and use a pencil to mark where you want to cut. Remember to stray away from drastic shorts surgery - you can always cut them shorter but you can never make them longer. So be weary!
Either way, this is an easy and cheap (a.k.a. free) way to get some mileage out of some old pants and update your summer wardrobe. Enjoy!