On Family Guy Season 13 Episode 8, "Our Idiot Brian," Brian falls from his usual intellectual throne at the head of the family. It all starts when Meg realizes that she needs help with her upcoming SATs, and doesn't know what to do.
The family sits down to watch a movie starring actors that make you go "oh," when you realize that they're still active. Meg interrupts to ask for help on her SATS, and Lois tells her that high school should be for worrying about your weight - not your grades. Brian advocates for education, while Peter just wants the TV back on.
At school, Meg asks her friends how she could do better on her SATs and one of them suggests paying another student to take it. Neil pops up, thinking he heard someone say "Jewish," but Meg realizes that she needs to ask Brian to help.
While Meg is home sweet talking Brian and peer pressuring him to go against his morales, Stewie chimes in to deconstruct her act. However, referencing his book, even it's just the cover, impresses Brian enough to help.
He falls for the flattery and goes to school dressed as Meg with some glasses and a pink beanie. No one notices the difference and he tries to mingle with the teens. He takes the test and is confident in his answers.
Meg reveals later on that he got a 1000/2400, and Brian is shocked. He gets called stupid by Chris, who then goes to inform the townfolk. One of the townfolk comments on how happy he is that the episode is about Brian and Stewie now, not Meg.
Brian gives in to his supposed stupidity and sinks down to Peter's level. After a lot of partying, he ends up in the hospital, only to find out that he's had a brain tumor this entire time.
Lois makes the argument that if he's been happy and enjoying himself this entire time, then he has the right not to get the tumor removed. Brian agrees and continues living the way he has been.
However, Stewie can't stand the loss of his best friend. He attempts various different ways of getting him to agree to to the surgery, and finally realizes that the simplest method would be probably work the best on an idiot.
He convinces Brian that they're going to the doctor's for a surgery that gives you "two weiners." Brian wants "two wieners" so that when watching Black Swan, he can point one at Natalie Portman and the other at fellow co-star, Mila Kunis.
After getting the surgery, Brian claims that he's happy. However, he doesn't hesitate in reminding Stewie that he could've just left him happy and at peace with his stupidity rather than bringing back to the harsh reality of being an alcoholic and the best friend of a baby.
Stewie claims that they have fun together.
Peter walks in, having undergone the "two wieners" surgery, and as he dances, his original penis falls off.