- “I'm Sherri. She's Terri. (Double balloon)”
- “You must be nice to them - they could surround you!”
- ―Bart Simpson.
Sherri and Terri Mackleberry are a pair of identical twin students of Springfield Elementary School. Terri is younger than Sherri by two seconds. They are in the same class as Bart, by Edna Krabbapel. They are a little bit strange and sometimes they speak in their own language. They will also not hesitate to berate Bart as seen in various episodes. No one knows whether one twin is Terri or Sherri. However, they are really triplets and the third one is out for revenge. Sherri and Terri have long, purple hair and always wear the same clothes.
- They both play the piccolo in the Springfield Elementary School band.
- They had once kissed Bart on the cheek to make him sing in front of the students on the bus in Homer's Odyssey.
- In Future-Drama, they are both seen in the prom, apparently both impregnated by Nelson Muntz (and their twin babies, despite being newborns, share Nelson's trademark "Ha ha!").
- In The Blue and the Gray, it is revealed that they are two-thirds of conjoined triplets, and that the third triplet is out seeking revenge against Sherri and Terri.
- Bart appears to have a crush on one of them, despite being berated by them.
- In Barthood, as a teenager, he makes out with Sherri and she reveals he is in a relationship with Terri, who she pretends to be suggesting Terri is the one he likes but this is non-canon.
- In "The Daughter Also Rises", Sherri and Terri engage in a version of "three card monte" by switching positions between their chairs at a table and disappearing occasionally below the table. As they continue with this act, Marge comments that it now appears that there are three of them. This could mean that the third triplet does exist and just showed up right there.
- In Yellow Subterfuge, Sherri and Terri's last names were revealed when Skinner holds a list of his students, two of which are the twins. http://imgur.com/bOcitQV