Zips and Eeloo are two aliens who have read a bunch of books about humans and watched a LOT of human TV. You could DEFINITELY say they are experts at all things human. They even have EXPERTS IN ALL THINGS HUMAN CERTIFICATES! And in all of the stories, Zips and Eeloo have learned that humans love friends, so now they are going to make a friend, too. But "making friends" is harder than it seems ... nowhere in any of the books have Zips and Eeloo learned how to make one, so they're going to try with milk jugs, tennis balls, and anything else they can find.