Marge has two older twin sisters, Patty and Selma Bouvier. Both sisters are single and live together in the Spinster City apartment complex and work at the DMV. The two chain-smoking twins have a strong, ongoing dislike of Marge's husband, Homer. They're quick to point out his short comings, and suspecting that Homer is as lazy in bed as he is around the house, they decided to give Marge a little present.
If there's one thing Selma and Patty know about, it's sex toys. Although Selma has been married several times, each of the marriages ended as a sham (Sideshow Bob, who tried to kill her), Troy McClure (who married as a publicity stunt), Disco Stu, Lionel Hutz, and even Grandpa. Her sex life remains wanting, and Patty, a lesbian, only love turned out to be, in fact, a man. Both women's sex life is dependent upon toys. They've ordered and tried out many over the years, and they knew just which one to get their sister Marge.
In their quest to find Marge a replacement for Homer, the twins have given Marge a special gift: a giant vibrating 15" dildo. With the satisfaction of the new toy, they hope, Marge will see the shortcomings of Homer's sexual prowess and ability to please her.
When Marge gets her present, she can't wait to try it out. With the help of some lube, she manages to work the first couple inches in of the 15" dildo. She's happy to have such supportive sisters and can't wait to share her new toy with Homer.