"Let's Play Tennis" is the 47th episode of the first season of Kaeloo, and 47th of the series overall.
Quack Quack plays tennis by himself, by running from one end of the court to the other to hit the ball. The others watch on, but find it difficult to turn their necks quickly enough. After a while, the ball, now burnt, lands on the ground.
Kaeloo tells Quack Quack that she finds it sad that he's playing alone, but he makes fun of the others saying that he's better than them at tennis. They get angry at him and challenge him to a tennis match the next day, and he agrees to participate. After he leaves, the others start to wonder how they will beat him at tennis.
Mr. Cat decides to train Kaeloo and Stumpy, so he starts by making them do exercises. At first, the exercises are fairly normal ones such as push-ups, but then he starts making them do unusual things like break dancing.
Then, he throws balls at them. Stumpy is unable to hit any of the balls, and he wonders why. Kaeloo points out that he doesn't have a racket to hit them with, so she gives him a racket and they both try to hit the balls. Finally, Stumpy manages to touch one of the balls with his racket, but it merely falls on the ground in front of him. Nevertheless, he considers himself as a tennis champion, and he pushes Kaeloo to the side and decides to play by himself.
Mr. Cat then loads a bazooka full of tennis balls and fires all of them at Stumpy. All of the balls hit Stumpy in the face, but he still thinks he is a champion. Kaeloo and Stumpy decide that they have made progress.
The next day, everyone meets on the tennis court. Kaeloo is the referee, and Stumpy is playing against Quack Quack. Kaeloo tells Quack Quack to serve the ball, but just as he is about to hit it, Mr. Cat shoots him with a bazooka. Kaeloo tells Mr. Cat that he isn't playing fair. Quack Quack serves the ball again, and Stumpy manages to hit it with the racket. However, the ball was served so forcefully that it continues to move in the direction it was served in, and Stumpy is sent flying. Mr. Cat tugs on the net with his finger and claims that the ball hit the net, but Kaeloo tells him that she saw what he did.
Kaeloo explains how points are awarded in tennis, and Mr. Cat and Stumpy get bored and go home. They return the next morning just as Kaeloo finishes talking. Unaware that they weren't there, she asks if they understood what she said, and they claim that they did.
Quack Quack and Stumpy continue to play, and Quack Quack continues ro hit the ball while doing various activities such as reading a book or watching TV. All the balls wind up in Stumpy's mouth. Stumpy congratulates Quack Quack on having won. Mr. Cat is incredulous that Stumpy would congratulate someone who beat him.
Kaeloo, Stumpy and Mr. Cat decide to re-watch the match and analyse how Quack Quack played. They watch the video, and Mr. Cat notices that Quack Quack picks up a ball, Quack Quack serves the ball, and Stumpy eats the ball. They watch it one more time in slow motion, and Stumpy thinks he looks handsome in slow motion. Mr. Cat disagrees, saying that Stumpy is normally ugly, but slow motion makes him look ugly for longer periods of time. Stumpy disregards what Mr. Cat says and decides to move in slow motion from then on.
Stumpy takes the role of referee, and Kaeloo starts to play against Quack Quack. Stumpy tells Kaeloo that she has to beat Quack Quack. Kaeloo weakly hits the ball, and Quack Quack hits it back to her. She misses, and Mr. Cat accuses Quack Quack of cheating. Kaeloo points put that he didn't cheat. Stumpy realizes that he is sitting really high above the ground, and then remembers that he has acrophobia and panics. Quack Quack hits the ball, and Kaeloo hits it back, and the ball lands on the net. Mr. Cat runs up to the court and blows on the ball and makes it land on the other side. Kaeloo asks him to stop playing favorites.
Stumpy thinks that if he moves in slow motion and jumps out of the chair, he will land in slow motion. Obviously, it doesn't work, and he falls quickly and hits the ground. Kaeloo hits the ball to Quack Quack, and Mr. Cat throws a bunch of sharp objects at him at the same rime. Quack Quack hits everything back.
Kaeloo starts to get angry at Mr. Cat, who is now impaled by all the sharp objects, but he just laughs her anger and the injuries off. He then threatens to shoot some yogurt with a bazooka if Quack Quack doesn't declare forfeit, so Quack Quack gives up. Mr. Cat announces that Kaeloo won, and Kaeloo gets angry since she didn't want to win by cheating.
She then transforms and beats him up into the shape of a ball. She and Quack Quack play tennis with him as the ball, and hit very hard on purpose. After the game is done, Mr. Cat, writhing in pain on the ground, reminds them that it was supposed to be a "friendly" match.
- Quack Quack
- Mr. Cat
- Bad Kaeloo appears to be genuinely worried about Mr. Cat after beating him up at the end of the episode.