This is a video demonstration of David Zarrouk's SAW robot. SAW stands for Single Actuator-Wave, because the worm is powered by a single motor that drives its wave movement though a rotating wheel. It can crawl, swim, and even climb narrow gaps. And, once some evil robot sympathizer figures out how to make the robots small enough, that narrow gap could very well be an unsuspecting person's asshole.
Keep going for a video demo.
Thanks to Sima, who agrees there should only be one kind of robot in the world: dead and melted to make swing-sets and other playground equipment.