The Karate Kidder is an episode of the ALVINNN!!! and The Chipmunks series.
Simon and Theodore are playing a board game when Alvin interrupts them with karate moves. Simon confines in Dave that Alvin may be overconfident in his abilities, and when Alvin tries to show off a move to Dave, the red-clad chipmunk is unable to escape his grip until Dave falls asleep dropping him. Disappointed, Alvin doesn't want to go to karate practice anymore. Miss Croner scowls Dave for crushing Alvin's confidence as Officer Dangus arrives about a cat food thief. Seeing as someone apparently returned the food, the elder reports Dave's "crime" to Dangus. The uniformed man also frowns on Dave's behavior and enters the Seville House in order to encourage Alvin to keep going to karate practice. Following the officer giving his full support to Alvin, his family still doubts his capabilities once he announces he's representing the town's dojo in an upcoming competition. They research his opponent, who appears to be a large man able to throw a car, so they visit the man to get him to call off the match only to irritate him. Given the failure, Dave talks to the karate instructor about removing Alvin from the competition and is once again lectured about destroying Alvin's mental state. On the way home, Simon suggests Alvin could sleep through the match for he would be too tired from practice beforehand. In the basement, Alvin duels with Cupcake until exhausted and fast asleep. Certain the match is over, Simon goes to wake Alvin and finds him gone; upstairs the local news reports a victory for the man Alvin was to fight. Shortly after, Alvin enters with Dangus excited for his victory over the man's son. With renewed confidence, Alvin uses one of his moves on the mailman causing Dave, Simon, and Theodore to yell "ALVINNN!!!"
- "The Beast Inside" 
- This episode's title is a reference to the 1984 movie Karate Kid.
- This is the first episode not to use the original series opening theme.
- Cupcake (Conquistadora) from Bully For You makes a reappearance.
- Officer Dangus receives two 10-16 calls on his radio, which means there's a domestic disturbance.
- A sneak peek clip was uploaded to Nick.com.