Season 4, Episode 15: Brian Goes Back to College

Recap: When it's revealed that Brian never finished college, Brian decides to return to obtain his last degree. However, he must deal with his temptations to cheat in order to pass the class. Meanwhile, Peter, Quagmire, Cleveland and Joe become the new "A-Team" after winning a costume contest.
When is it on: Current and future airings of Family Guy.

Season 5, Episode 6: Prick Up Your Ears

Recap: Lois volunteers to teach sex-ed class after discovering Chris has been getting bad information on sex, though she is soon replaced by a Church spokesman. Meanwhile, Meg and her new boyfriend take an abstinence pledge but still manage to find a loophole, and Stewie goes to great lengths to destroy the Tooth Fairy.