Family Guy S04E02 - Fast Times at Buddy Cianci Jr. High

When Chris' teacher wins the lotto and quits, Brian fills in as the substitute. All's well until Brian is moved to another class where he must teach troubled kids to aim low. Meanwhile, Chris is instantly smitten with his new teacher, Mrs. Lockhart, who promises to be with him if he kills her husband. But when Lois finds the teacher's written instructions in Chris' laundry, she and Stewie conspire together to find answers and teach Chris a lesson.