Lucky Day is an episode of the ALVINNN!!! and The Chipmunks series.
Alvin's luck goes from bad to worse after Theodore finds a four-leaf clover.
When Alvin beats a robot playing ping-pong, Simon engages the advance mode. Meanwhile Theodore arrives with a four-leaf clover, stealing everyone's attention away from Alvin. Theodore explains his luck has changed already, but Alvin denies the existence of luck. Dave informs Theo of a package and they learn he won first prize from The Kids Can Cook Recipe Contest, which is a new bike. Jeanette points out his lost Talking Teddy hat and Theo's convinced it's the clovers doing. Alvin continues to deny any existence of luck just as he slips hitting a table and breaking a mirror. The next day, Alvin loses his wallet and gets an 'F' on a test, while Theodore finds $20 and receives an A+ in his test; the same night Alvin has a nightmare while Theo has a pleasant dream in Candyland. The following morning, Alvin continues to have bad luck, from his favorite cereal being gone to all sports being cancelled while Theodore continues to have good luck. Once he breaks a chair when he sits down, Alvin loses it and searches online for lucky items. He receives the golden horseshoe just as a bird poops on him and he's sprayed with water after throwing the horseshoe. He then sets out to catch a ladybug but is bitten on the nose by a beetle by mistake. Desperate for good luck, Alvin steals the clover. While he does roll a seven with a pair of dice, a baseball breaks a window and hits him in the eye; all the while Theo's luck is unchanged. The Chipmunks and The Chipettes explain to Alvin in bed that the four-leaf clover was just an April Fools joke and that Theo's luck was due to him being an optimist. Understanding, Alvin nervously reveals he placed a large bet on a horse with Dave's credit card after he first took the four-leaf clover.
- "It's a Lucky Day" 
- The instrumental for "Look at Me Now" briefly plays during Alvin's victory dance.
- Goof: The sprinkler suddenly turns on when it's hit by the rake.
- Series Running Gag: Theodore says the wrong word/phrase - Optometrist and opposite instead of optimist.
- Theodore is confirmed to be an optimist in the series, according to this episode.