Nose Pickers from Outer Space by Gordan Korman

A Gripping, Almost Real Life Tale!!! When Devin Hunter signs up for the national exchange student program, he doesn't count on ending up with a nerdy kid who eats paper, talks to the dog and worst of all, cannot keep his finger out of his nose. But Stan isn't really a student and his unhygenic habit may be the key to saving the world. By Gordan Korman: a man recently returned from the far reaches of OUTER SPACE!