The episode starts off with Randy and Howard discussing their best friend status. Thanks to their planning ahead, Randy and Howard have become buddies in every class so far - once they become "baking buddies" in Home Economics class, they will have partnered for every possible class, which the boys have termed the "Class-fecta", as a sign of their friendship. Howard reveals that he even made matching chef hats for the both of them, monogrammed with their names, and they excitedly go into Home EC, taught by Mr. and Mrs. Driscoll. A new exchange student named Franz joins the class, and cheerily greets the students, then asks them to say "Hello". The others awkwardly oblige him, and Howard is briefly suspicious about him. Randy suggests that Howard relax, but is soon distracted by the NinjaNomicon glowing. Before Randy can shloomp, Howard insists that Randy ignore the book until Driscoll officially partners them for the class. Randy dismisses the idea, telling Howard that it is his responsibility and he likes being the ninja and will take his duty, also claiming Howard just needed to tell the teacher that they were partners. The two boys fight over the Nomicon, culminating in Randy declaring that the "Class-fecta" isn't actually a thing before shloomping into the book, offending Howard. Meanwhile, Viceroy tells McFist that he had created a robot in which has the adorability of a bunny, the naivety of a koala, and the weaselness of a weasel - in short, a robot designed to befriend people. By encouraging people to befriend it, the robot can record voices of people it encounters through a microphone in its finger, then compare the voice samples to a recording of the Ninja saying, "Say hello to my Ninja Eye Poke!" to identify the Ninja. The robot is revealed to be Franz.
In the Nomicon, Randy learns the lesson, "The most dangerous enemy often wears the mask of an ally." Randy thinks that the book is talking about Howard and complains about how Howard doesn't seem to take his role as the Ninja seriously. After falling out of the cabinet which he was in, Randy finds out that Howard has replaced him with Franz, breaking their record of being partners in every subject and classes. Randy is angry at Howard for leaving without a partner, to which Howard mentions that Randy didn't seem to care about their partnership. During lunch, Howard also replaces Randy's spot at the table with Franz, much to Randy's indignation.
Randy insists to Howard that Howard is "being an enemy", which Howard does not take well and continues ignoring Randy. Randy's annoyance only increases as Franz continues befriending everyone, getting them to say "Hello" and congratulating them for doing so. Everyone, including Bash, falls for the robot's friendly facade, and begins mimicking Franz with the exception of Randy. Irritated, Randy goes over to Franz, explaining his "best friend" status with Howard and telling Franz to play his "Hello" game somewhere else. This inadvertently gives Franz a sample of Randy saying "Hello", which Franz matches with the Ninja's voice sample. Franz greets Randy, saying "Hello, Ninja!" much to Randy's horror.
Back at the lab, a computer terminal sounds an alarm saying that Franz has identified the Ninja, but McFist impatiently punches the screen and destroys it when it doesn't give a name. Viceroy is extremely annoyed by the fact of this and attempts to fix the computer. Back at school, Randy tries to play off Franz's claim as Howard is offended that Randy revealed his secret to impress Franz, but McFist deploys Chainsaw Werewolves to retrieve Franz. As the werewolves attack and "kidnap" Franz, Randy goes Ninja to save him. He destroys two werewolves instantly and melts the other one in a batch of chili made by the lunch lady. Some of the chili spills on Franz's face, melting his exterior and revealing he robotic insides. Randy realizes that the Nomicon wasn't warning him about Howard, but of Franz. As Randy and Franz battle, Viceroy manages to fix the computer and commences downloading the information from Franz, which Franz declares in glee. Franz knocks Randy into a back room, holding Randy on a ledge hanging precariously over a huge vat of chili.
Howard intervenes by hitting Franz with a lunch tray; while the hit fails to deter Franz and instead causes Franz to advance towards Howard, the distraction is enough for Randy to toss Franz into the chili with his scarf, causing Franz to melt and disintegrate. This interrupts Franz's data transmission to Viceroy's computer, much to the frustration of McFist.
Back in Home Ec, the boys apologize to each other and reconcile as baking buddies. Howard takes out a cake made from the imprint of Franz's face and Randy uses the red icing to color the eye. Flute Girl passes by, telling them that they are idiots. They happily shout that they are buddies, causing the whole class to look at them.
- The title is a pun of the phrase "new kid on the block."
- Howard laughs every time someone says "duty." This joke had already appeared once during "Wave Slayers".
- This is the second appearance of Viceroy's koala. The first time was in "Night of the Living McFizzles".
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