Sleeping Freshmen Never Lie, by David Lubar (Dutton 2005)(tweener).
Scott Hudson is beginning his freshman year of high school. As if losing friends, gaining bullies, being dragged into too many activities, and missing sleep aren't bad enough, his mother's announced she's having a baby. Clearly, he's in way over his head...A charming and deeply funny novel.
Cyn has an interview with David Lubar here.