Stan asks Chef when the best age for kids to become sexually active, he states that the right age is 17, which happens to be the age of consent in Colorado.
The sex book that Mr. Mackey and Ms. Choksondik are reading is a real book titled "Our Sexuality" by Robert L. Crooks and Karla Baur.
By his own admission in the dialog when Mr. Mackey is at the front of the class giving a lecture on sexual intercourse, Mr. Mackey places his age at about the age of 40, given that he was about 19 when he last had intercourse, and that it had been about 21 years since.
Stan gets grounded for ten months for masturbating their dog.