Dav Pilkey. Scholastic/Blue Sky, $16.95 (144p) ISBN 0-439-04995-4

Fourth-grade cut-ups Harold and George and their principal-turned-superhero are as funny as ever in Pilkey's third Captain Underpants caper. (For those in the dark, the superhero in question is an underwear-clad, toilet-paper-toting crusader for 'Truth, Justice, and ALL that is Preshrunk and Cottony). As in the earlier installments, this zany tale adopts a variety of formats, including sprightly illustrated text; reproductions of the two boys' homemade comic books; and 'flip-o-rama' pages that replicate 'world-famous cheesy animation technique.' Captain Underpants and his errant students here go up against a trio of aliens posing as lunch ladies. Suddenly students begin turning into 'zombie nerds': 'Look, says George, 'They're all wearing broken eyeglasses held together with masking tape and they've got vinyl pocket protectors!!! It's all part of the aliens' quest to take over the world: 'It won't be long now, says the evil Klax. 'Tomorrow we'll feed them Super Evil Rapid-Growth Juice! Then they will grow to the size of Zleqxisfp trees. Those with a limited tolerance for the silly need not apply to the Captain Underpants fan club, yet its legion members will plunge happily into his latest bumbling adventure. Ages 7-10. (Sept.)