Wrath of the Wicked Wedgie Woman by Dav Pilkey (Paperback)

George and Harold are always good at using their imaginations, and that drives their mean homeroom teacher, Ms. Ribble, crazy But this time, they've come up with much more than a silly prank -- they've accidentally created a MONSTER With her horrendous hairdo and two rabid robots, Wedgie Woman is well on her way to world domination, and only the Waistband Warrior can stop her.