Whoa, this is the most interesting video from Engineer Guy. It's about the design of the classic baby diaper and how the different layers of fabric all work together to whisk away moisture from a baby's bottom and keep it away for up to 9 hours. How does it work? Well, in large part thanks to really advanced fabrics that have properties made specifically to absorb liquid. And it all works effortlessly no matter if the baby is lying on its stomach or on its back (meaning, the liquid travels away from the baby's skin independent of gravity).
Pretty cool stuff here and a really thorough explanation of how a diaper works.