Bart had gotten another bad grade. All he had to do was enter the Science Fair and get a good grade so he could improve his average and go on the family trip. Lisa wasn’t going to help him, so Bart decided to go to Professor Frink. Without the professor seeing him, Bart took a seed that was supposed to mature the neurons in his brain to make him smarter. However, the next day Bart grew in intelligence and body; he had become an adult!

Because of his current state, Bart doesn’t have to go to school… but he also couldn’t go on the family cruise. To avoid leaving him alone at home, Marge decided to skip the family trip. Although her intentions were quite innocent, Marge began to get excited by analyzing her son’s muscular body, even going so far as to spy on him while he was taking a bath, masturbating in the middle of the hallway, imagining everything she would do with Bart’s hard cock between her tits.

That same night, Marge tried to vent all her sexual frustration on her husband, but Homer was inconsiderate as he came inside her, without giving her an orgasm first. When Lisa and Homer left, it was clear that Bart was pretty depressed about having made his mother miss her vacation, so she tried to cheer him up as best she could by cleaning the attic together. She even came up with the idea of ​​modeling her old clothes for him as a way to entertain herself.

After Bart made fun of Marge for how nerdy she looked in her old school clothes, Marge decided to show him her gym clothes that left little to the imagination. Bart himself seemed to think so, as a hard erection emerged from his pants. Although he was worried, Marge assured him that she would take care of his problem, and went back to the bedroom to show her son some new clothes, this time a sexy swimsuit that barely covered his privates.

Although they were both nervous about their feelings, this time they didn’t hesitate and Marge pulled her son’s erection out of his pants to start giving him oral sex. Bart didn’t stay behind and with his masculine hands, he started to rub and squeeze his mother’s huge breasts, lowering his hands to her pussy to masturbate him. Marge didn’t wait a moment to start riding Bart’s big cock.

It only took a couple of minutes for Bart to release his semen explosion inside her. Unlike Homer who was exhausted after his first release, Bart was still somewhat vigorous and buried his cock now in Marge’s big ass, fucking her while pulling her hair. She did nothing but moan, satisfied and proud that her little son was already a man, enjoying riding him, looking into his eyes.

After a few days, Professor Frink already had the cure for Bart. However, that would not be the end of Marge and Bart’s new relationship, because she would make sure to steal those growth seeds from the professor to use on her son at her convenience.