S05E18 - Zach and the Alien Invaders
Synopsis
Zach, the Turtles' young friend, and honorary fifth Turtle, is infatuated with comic books, especially ""The Alien Invaders""... but the boy has ""cried wolf"" once too often as he seems to see aliens everywhere.
Zach ""retires"" his Turtle costume when his parents enroll him in the Ten-Hut Military Academy where they hope he will learn some discipline and live in the real world.
But after Zach arrives, he discovers that all his fellow cadets are zombies thanks to two aliens: Wingnut and Screwloose, who are disguised as Colonel Clout and Sergeant Rambo. Wingnut and Screwloose plan to conquer Earth using their ""Mind Changer"" on the young cadets.
Zach calls the police when Wingnut and Screwloose unleash a Robotic Cockroach onto The City, but they do not believe him. The only ones who might believe him are the Turtles, but he is captured before he can convince them that he is telling the truth.
It is not until the Robotic Cockroach starts attacking some construction workers downtown that Zach's