Luigi's Secret is the first episode of SML Shorts.
Mama Luigi is shown holding a CD. Mario asks him if he can see it. However Mama Luigi says because it's too embarrassing, so he finds a place to hide it. Then he finds the perfect hiding spot, but Mario quickly finds it since Mama Luigi put it under a paper that says "The CD is not under this paper, Love Mama Luigi". Mario then watches the video, which the video shows Mama Luigi and Bowser singing and dancing. Mario then finds it embarrassing, and decides to put it to YouTube. Suddenly, Bowser and Mama Luigi come in the scene and hit Mario. At the end, it shows that Mario posted the video onto YouTube and it got over 10,000,000 views, but then it got deleted by YouTube for copyright.
- This video marks the first SML Short.
- The song Mama Luigi and Bowser sang was If I Were A Boy by Beyoncé.
- Despite this video being called "Luigi's" Secret, this video featured Mama Luigi.
- At the end of the episode, Zeke's face was shown When he was controlling Bowser and Mama Luigi.