Kiss, Kiss, Bark! by Kim Williams Justesen

Mattie has a couple of dilemmas. First (sigh), her parents are making her babysit her humiliating younger brother nearly nonstop. What could BE more awful than the constant company of a 4-year-old brother who acts like a dog? Then, her best friends brother begins to show serious interest in her. Mattie thinks all her prayers have come true, that is, until her best friend