Annie's pens are purple gel gripped writing utensils used by Annie Edison for her classes at Greendale Community College. They were chosen for their color and style as well as their comfortable use. The pens were one of Annie's favorite school supplies. She would often lend them to other study group members and the disappearance of one of the pens in the study group's second year at Greendale together led to a huge fight amongst them as to who was responsible. The pens' first appearance was in the Season Two episode "Cooperative Calligraphy".
During the study group's second year together, the study group had just finished work on another diorama for Anthropology class. They were about to leave when Annie stopped them. One of Annie's pen's had gone missing and she believed someone in the group had borrowed it without returning it. Everyone denied they had it and were eager to go, as they all had personal matters to attend to. Annie stubbornly refused to drop the matter and again demanded to know who had her pen. Shirley tried to placate Annie by insisting that from now on they will be more respectful of others' property. However, when everyone tried to leave again, Annie let out a piercing scream stopping them dead in their tracks.
Even after a search of the room and all of the study group members' backpacks, they were unable to find it. Annie remained insistent that someone in the group had to have been responsible. A subsequent investigation, strip search and a look inside the casts Pierce had for his then broken legs still turned up nothing. The experience ended up causing a lot of emotional turmoil for all involved. Ultimately, Jeff suggested they accept Troy's theory that a ghost took it. Wanting to see some resolution to the conflict the stolen pen created, everyone eagerly agreed ("Cooperative Calligraphy"). It was not until later in the school year that the true culprit was revealed.
When the study group was working on their final diorama of the semester for Anthropology class, Troy's pet monkey Annie's Boobs stole his paintbrush. The animal escaped into the air vents and was pursued by an oiled-up Ben Chang. While following the monkey's trail, Chang came across a pile of loot Annie's Boobs had stolen. It was made up of various personal items stolen from the study group over the past two years. A collection of Annie's purple pens were included in the find which Chang brought back to the study group. Britta personally handed them over to Annie, who was excited to have them returned ("Paradigms of Human Memory").