Let's Save the World You Jerk! is the second part of the 25th episode in the second season of Dexter's Laboratory. In this episode, Dexter and Mandark try to stop a giant asteroid from hitting Earth.
A giant asteroid is headed toward Earth. Dexter goes into space in his giant robot, Robo-Dexo 2000 and uses his beam to stop the asteroid, but he breaks it into a group of asteroids and they hit his giant robot. Dexter calls someone to stop the asteroids from hitting the Earth, and that person is Mandark. Mandark goes in his giant robot to stop the asteroids but they hit his robot. Dexter and Mandark have to team up together to prevent the asteroids from destroying the Earth. They build a heavy robot to get rid of all the asteroids and they go up in space together to stop the asteroids. They fail due to their arguing and fighting, and the asteroids hit the Earth and when the asteroids hit the Earth, they collide with it and break it up into pieces. Dexter and Mandark continue to fight.