My Sister The Weirdo is an episode of the ALVINNN!!! and The Chipmunks series.
Jeanette wants to give a toast to Brittany at her upcoming party. But Jeanette is so shy, she seeks advice from the most confident person she knows...ALVIN. But his advice embarrasses Brittany to the point where she decides not to invite Jeanette to her party.
While Brittany is stressing about a party for herself, Jeanette is worried about her oral report, which has stressed out her sisters as she keeps practicing it repeatedly. After Alvin talks about a secret agent, Jeanette tries to talk about courage though it's clear she's extremely nervous and does poorly. At the end of class, Brittany lies to her friends by saying Jeanette's been in multiple tree accidents and suffers from head trauma, and Simon tries to help her. Jeanette runs into her locker and asks for Alvin's help (as he's the most confident person she knows), to Simon's disappointment. Alvin offers her advice as Simon role-plays as Jeanette. His advice to her consists mainly of doing anything to be noticed, even if it embarrasses herself. Alvin finds out about Brittany's lie and offers to keep silent if she leaves Jeanette alone and be his personal assistant. Jeanette does her best to follow Alvin's advice: tap dances, acts as a mime, cheerleads, dresses as a clown, and raps. Though Brittany's had enough of Jeanette acting weird, Jeanette, Alvin, and Simon have another session only for Brittany to stumble into Simon dressed as Jeanette creating an awkward moment. Back at school, Jeanette discovers Brittany's secret and that she's not invited to her sister's party and leaves heartbroken. Brittany kicks off her party but is upset with what she said. She calls her sister out, apologies, and learns everything Jeanette's done was to work up the confidence to give Brittany a toast in front of her friends. Jeanette informs her she couldn't have done it without Alvin. Brittany, surprised to learn of Alvin's involvement, confronts Alvin as Simon attempts to explain why he was dressed as Jeanette.
- Jeanette's essay on the "Bravest Person You Know" may have been about Rosa Parks, as one of the words she mentions is bus.
- The episode's plot is similar to the '80s episode Sisters.
- Goof: When Brittany says Jeanette won't be going to her party, Theodore is seen sitting beside Alvin, but when Jeanette leaves the classroom, Theodore disappears.
- Part of the Alvin Vs. Brittany and Driving Dave Crazy DVD.
- Goof: In the beginning, when Brittany and Eleanor are saying, "NO!", Brittany's arm goes through the pillow.