The twins are quite bright students (they even have their own language known as cryptophasia in most areas of the spectrum of twins) and are often very conniving and mean, even to each other. When it comes to Bart they are quite stuck up, and never miss an opportunity to berate him. They fed Bart intentionally false information on American history, however both girls correctly guessed that Bart had not prepared himself for a test and was looking to get all the answers from a student who studied, so the prank was arguably to teach Bart a lesson in slacking; since if he had studied he would have realized the information was false.
Principal Skinner apparently considers Sherri smarter or more talented than Terri, because in Simpson Tide he announces, "In the event of nuclear war, we can only save our best, and brightest. Therefore, space in the fallout shelter will be reserved for: Lisa Simpson, Martin Prince, our championship kickball team, and Sherri, but not Terri."
Bart appears to have a crush on one of them. Sherri (or possibly Terri) referred to Bart as an ugly, smelly dork, but was convinced by Homer to go on a date with Bart after he told her that neither she nor Bart could do much better. One of the twins stated that her sister had a crush on Bart it is unknown if this is the truth or if it is just teasing. She also has a "boy crazy" cousin who has a crush on Bart.
When it comes to Lisa they are just as inconsistent. One minute they will be friends on the schoolyard playing together and the next they will be ganging up on her. More often than not it is the latter, usually not including Lisa because she is too smart or too weird. Once they said her butt was too fat causing Lisa to go on a diet.
In the Simpsons and Family Guy Crossover episode Sherri is pushed by a kid into Terri causing Otto to hit them with his school bus.
Sherri has dark purple hair, eye color unknown due to the cartoon series having the characters with only black pupils, pale yellow skin and wears a purple dress with matching purple Mary Jane shoes, a matching purple headband, and short white socks.
The contents of this article or section are considered to be non-canon and therefore may not have actually happened/existed.
In Barthood, as a teenager she attends a party thrown by Bart Simpson. He makes advances on her thinking she is Terri, she laughs and they make out in the closet while doing so she mentions he kisses just like Terri said he does. Bart was shocked to find out that she wasn't Terri as she confirms by stating she was Sherri though she tried to seduce him in continuing the encounter stating "The further we go the more you'll know the difference". A creeped out Bart rejected her and left the closet, to her shock. She got over it very quickly as she was seen making out with another boy.
Professor Frink shows Bart and Lisa a possible future with his astrology machine. It is revealed that Nelson simultaneously dated and impregnated both Sherri and her sister, who bore him four children (two sets of twins, naturally) shortly before Nelson's high school graduation. He abandoned them during Bart's graduation party, using the same statement his father said to him before abandoning him.
The Simpsons Arcade game
Sherri and Terri appear in stage 1 and 2 carrying a burger in a plate for the Simpsons to gain their health.
Sherri and Terri also appear as one of the holders of the three Sparklemon that Homer and Lisa must defeat.
Behind the Laughter
They have similarities to the Grady Twins (ghost girls) Danny sees in Stanley Kubrick's adaptation The Shining, of Stephen King's novel of the same name. In a deleted scene of the parody of the Shining called "Treehouse of Horror V" they are ghost twins seen by Bart. They also take on this role in The Simpsons Game; they are in a game engine elevator saying "Come play with us, Simpsons".
Matt Groening said Sherri is always on the left in an episode commentary.
Both she and Terri bear some resemblance to the twins Patty and Selma, as both hold an enjoyment for tormenting the males of the Simpson family, but for different reasons, and have a close relative who have a romantic crush on one of the Simpsons.
It is implied that Sherri and Terri are not actually twins, but two thirds of conjoined triplets, although this is conjectural, and should be considered non-canon until said 'sister' officially appears.
She apparently doesn't like Arby's restaurants, and would only eat there if she were starving.