Unlike marathons and triathlons run on roads and trails, obstacle races cover far shorter distances but ask participants to do far crazier things.

WSJ: Office Workers Run Extreme Obstacle Courses

You might say that Walmart would never, ever start hawking its own e-readers, but crazier things have happened -- Best Buy has an entire brand devoted to in-house goods, and Amazon itself has expanded from an online storefront for laundry detergent and bestselling novels to a bona fide hardware mainstay.

ENGADGET: Walmart to stop selling Amazon's Kindle line of readers and tablets