To spoof the body-building mania, Browne gives us sheepish, stoop-shouldered, weakling chimpanzee Willy, who's forever saying "" 'I'm sorry,' even when it wasn't his fault."" Called a wimp by ""the suburan gorilla gang"" (this British suburb, be advised, is a concrete wasteland), Willy sets out to build himself up--through a regimen of exercises, jogging, dieting (only bananas), aerobic dancing, boxing, and weight-lifting that, for a skinny little chimp, is pretty funny. (Not that Willy looks any funnier than the gorilla-bruisers he measures himself against.) Willy does finally develop a spectacular physique, and a self-confident stride. The suburban gorillas bothering girl-chimp Millie flee at his approach, and she calls him her hero. But when Willy is priding himself on his new stature, he walls smack into a lamp post--and, wimp-like, apologizes. To an extent, then, the book is a comic strip with a single haw-haw punch line. It also works, though, as a timely laugh at body-over-mind.