The fourth-grade boys are caught "milking" dogs (masturbating them) after Cartman mistakenly labels the act a "trick".
Ms. Choksondik's frightening lessons convince the girls that boys are carriers of deadly diseases. Believing they must wear protection at all times to avoid "the AIDS," the boys begin wearing condoms constantly. This misunderstanding escalates into an all-out "gender war" involving flamethrowers and nail guns. Episode 07: Proper Condom Use
While the children are terrified of sexual contact, Mr. Mackey and Ms. Choksondik—both originally portrayed as sexually inexperienced—develop a sudden and grotesque romantic relationship. Real-World "Proper Condom Use" Guide Episode 07: Proper Condom Use