Blobheads Go Boing! by Paul Stewart
Living with aliens isn't easy. Billy Barnes is getting fed up with the Blobheads - Zerek, Kerek and Derek. Their very important mission is always getting him into all kinds of trouble. They think his baby brother is the Most High Emperor of the Universe; their ridiculous disguises are just, well, ridiculous. And every time they try to help out, disaster is just around the corner. But wouldn't Billy's life be boring without the Blobheads?