Jennifer Joy, also known under J.J., was a friend of Max when she attended school during School's Out - Forever.
While in the lunch line during the Flock's first day at school, a girl asked Max where she got her hair done. Max responded by saying that she got it done in her bathroom, making the girl laugh. After putting a green apple on her lunch tray, she clarified that she meant Max's blond hair streaks. Max was unaware that she even had streaks up until this point and said that it must have been the sun. The girl called Max lucky, then introduced herself as J.J., saying also that "Max" was a cool, sporty, and sophisticated name. She soon pointed at an empty table, saying that they could sit there, otherwise they'd have to deal with "Chari and her gang". It wasn't until Max was halfway into her lunch that she realized she'd been talking to J.J. for thirty minutes—she'd made a new friend.
The next day, J.J. informed Max that the entire school was going on a field trip to the White House, meaning there would be no classes, no lectures, and "probably" no homework.
J.J. also told Max towards the end of the field trip that they had ten minutes to buy souvenirs.
Several weeks later, when the principal announced that "Jeff" had gone missing, J.J. told Max that she was sorry, and asked what happened. Max said that she didn't want to talk about it, so J.J. told everyone to back off and give her some space.
J.J. was described as being pale and skinny.
- J.J. liked banana pudding.
- It was hinted that she didn't like her name, as when she first introduced herself, she also said, "What were my parents thinking?"
- She had at least one sibling, having mentioned a brother.
- She wasn't mentioned after the second book.