Increasing word power sounds like one of those dreary chores best palmed off on somebody else. "The Yo Momma Vocabulary Builder, " the first in Fall Media's series of irreverent, educational books, makes the activity not only endurable but irresistible. The authors use classic dissing and one-upmanship to slyly introduce young readers to a wide range of words. A typical entry, for "emaciated," first presents the word as a joke ("Yo momma's so "emaciated, " she can hula hoop in a fruit loop."). The pronunciation is then given, along with a detailed, humor-inflected definition ("too skinny . . . skeletal") that invokes pop culture phenomena like supermodels, the Olson twins, Gollum from "Lord of the Rings, " and Ally McBeal. The book ties neatly into the "Yo Momma" phenomenon seen in recent MTV shows as well as books and games, and is an ideal gift choice for parents and educators looking to give young people a book they'll enjoy and share.