It's My Party is an episode of the ALVINNN!!! and The Chipmunks series.
After blaring a trumpet to get the class's attention, Kevin invites all the guys to his birthday party, which he nervously proclaims is a paintball battle. Miss Smith bores the class with a history lesson as Alvin daydreams about paintball. He's woken by Kevin, who chose him to be on his team, though Alvin's not thrilled. Kevin stops by the Seville House to confess he only wanted to look cool because his real party was going to be lame. The Chipmunks agree to help their friend prepare for the battle, but Kevin lacks everything needed for one, including experience. Alvin offers their home for the battle given Dave will be at an all-day parent-teacher conference. To prep for the party, Alvin teaches Kevin while Simon manufactures paintballs with removalable paint. Alvin rallies the team only to interrupted by Eleanor, who's interested in playing. In the first round they are annihilated though in the second they experience a comeback, despite Theodore expressing his displeasure. Following a shocking defeat of Derek's team, everyone discovers Eleanor took Theodore's place and is extremely skilled at paintball. Derek refuses to accept the deception so he and Kevin agree to a duel. Kevin wins just as Dave opens the door to discover the mess and that the paint doesn't come off. Back at school, Kevin thanks Alvin shortly before Derek pesters Eleanor to join the football team.
- "Never Backing Down" 
- This episode's title may be based upon Lesley Gore's "It's My Party."
- A sneak-peek clip was released on Nick.com.
- Running Gag: Alvin is interrupted every time he attempts to give a rallying speech to his team.
- When this episode premiered in the US, it aired with a rerun of Held Back.