First contact is exciting…but what if the ETs are real buttheads?Lloyd and Josh start a blog, The Peaceful Extraterrestrial's Guide to Earth, to invite aliens to Earth, explaining such topics of Earth culture as games, being sick, holidays, old ladies, and bathrooms. When two actual aliens with butts where their heads should be and faces on their rears answer the call, life gets complicated. IAmAWeenieBurger speaks English, but Doodoofartmama communicates only by farting; the species has 142 excretory functions. They claim that they are on Earth to meet Josh and Lloyd, play video games, and help the boys get the better of Quentin, a big, conceited jerk in their class who excels at everything. Naturally, that's not all. When threatened with exposure, the smelly aliens (who've already gotten the boys in a pile of trouble) send out a fart-call to 70 billion of their butthead buddies to join an invasion. Can Josh and Lloyd save every human on Earth from menial (and repulsive) servitude? Mahoney's over-the-top romp, with footnoted blog posts that appear at the rear, will cause giggle and snicker overload in its target audience. Josh narrates in a believably snarky 12-year-old voice, and he, Lloyd, and their classmates all come across as real kids with real-kid senses of humor. Race goes unmentioned, but the cover illustration indicates that one boy presents black and the other white.Most grown-ups will hate this, butt that's half the fun. (Science fiction. 9-12)

Gr 3-6 Forget the Voyager space probe and its Golden Record: alien interest in Earth is piqued by the "please visit our planet" blog written by Josh and Lloyd, sixth grade self-described underachievers. Answering the boys' invitation are aliens Doodoofartmama and IAmAWeenieBurger, whose butts are on their heads, speak in farts, and have a talent for defecating. Mahoney ( My Rotten Stepbrother Ruined Cinderella ) cheerfully aims low and single-mindedly hits his scatological mark at the expense of character development and setting. It's surprising that a "fun" novel's pace drags for the first 100 pages until Josh and Lloyd realize the aliens' visit may not be friendly after all. A gratuitous mention of boobs makes for an awkward moment in otherwise PG-rated content. The crude humor makes a noticeable shift in the novel's appendix, written as Josh and Lloyd's blog posts. Their suddenly witty riffs on topics from why to avoid sea salt to how the country of Chad got its name read more like Mahoney's adult ruminations than those of sixth graders. VERDICT Order where readers can't get enough of fatuous gross-out humor. Marybeth Kozikowski, Sachem Public Library, Holbrook, NY