"Robot in Waiting!" (海賊港の伏兵 Kaizoku Minato no Fukuhei, lit. "Ambush in the Pirate Harbor") is the seventy-fifth chapter of the Dragon Ball manga.
The harbor is huge, there is a dock with a huge ship, building, and cars. Bulma thinks it must have been the pirates’ base, and Krillin thinks the treasure is somewhere in here. They talk about the harbor some more, while Blue watches on, thinking about killing them and getting the Dragon Ball and the treasure. Goku senses something, and Blue gets scared, but Goku tells Krillin it is not the Red Ribbon Army, since it is not human. Then a Pirate Robot bursts out of the building, with a gun for a left arm and a sword in his right hand. It swipes at them with the sword, and they just barely dodge it. Bulma knew there would be ghosts here, but Krillin says it is a robot.
They dodge the bullets as the robot starts to fire at them and Goku rushes at it, kicking it in the back of the head. Then Krillin chops the blade of the sword off with his hand, and the two of them prepare to attack its legs. Blue notes their use of kenpō, and then the robot slugs Krillin in the face and knocks him back a few feet. Krillin thinks it is strong, and they prepare to attack while Bulma watches on. The pirate robot fires at them some more, and as they hide behind some crates, Goku tells Krillin to go find the Dragon Ball with Bulma while he takes care of the robot. Goku jump kicks the robot into the water, and Krillin and Bulma take the opportunity to run away, and Blue follows them at a safe distance. Goku looks down into the water, and the robot’s tail pulls him down below and starts to electrocute him. Then Goku breaks off the tail and jumps to the surface, and decides to take Nyoi-Bō up to the roof of the building. The robot jumps out of the water and looks around. Goku dives straight down at it and punches straight through the robot, causing it to explode.
Goku runs to try to catch up with the others. Meanwhile, Krillin notices that explosion is causing the foundation to crack. He and Bulma run like hell, and when they come to a fork in the path, Krillin marks the direction they take for Goku. When Blue catches up, he erases the arrow and draws a new one pointing in the opposite direction. Soon after, Goku notices the arrow and heads left instead of right.