It is Stump Day, the Mewni equivalent to Christmas, and all of Butterfly Castle is glad to celebrate it, especially Star who is ecstatic about the holiday. As revealed by River, Stump Day is the day that the first Mewman settlers came to Mewni. They quickly began to argue and were going to split up, but a terrible storm came and they were forced to look to a giant stump for shelter. Afterwards, they carved their initials into the stump and since then the Mewmans have stayed together and celebrated the stump. Later that night, Marco awakens Star to help with a window, but instead takes her to the living room to reveal that he, along with Tom, Pony Head, Kelly, Janna and StarFan 13 have all set up a Quinceañera for her as it is also her birthday. To their surprise Star becomes upset and proceeds to tell everyone to put up the decorations and continue to celebrate Stump Day.
Star tells that Stump day is important and that if they do not stop, the Stump will be very angry. Tom, Pony Head and Janna tell Marco that this is just a childhood thing to keep children quiet and that they find it amusing that Star still believes in this. Marco tries to get her to stop, especially since he ported a mariachi band, but eventually Pony Head and Tom turn on Marco, telling him that he did not consider what Star wanted. Marco soon insults Tom by stating that he did not even think of something for her, even though he is her boyfriend. This angers Tom and soon they both get into a fight. Kelly insults Janna for taking the event lightly while Janna makes fun of Kelly because Marco is fighting Tom over Star instead of her. Tad reveals he is still in Kelly's hair and Pony Head once again complains about the lack of attention.
Star tries to quell the situation, but everyone is too busy arguing. Eventually, Janna tosses the stump into the fireplace to warm them up, resulting in a giant Stump manifesting in the room and attacking everyone. As everyone tries to renounce disbelieving the Stump, River and Moon arrive, where they reveal that they too did not believe in the Stump, shocking Star ("Honey, it's a stump!"). As everyone apologizes to each other, they all hold hands until the Stump magically disappears. Marco declares that their love for on another saved them, but Star tells them it is because it was midnight and Stump Day is over. Star thanks Marco anyway for the party and he calls the mariachi band out to continue celebrating her Quinceañera.
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Dana Davis as Kelly
- Abby Elliott as Janna Ordonia
- Grey DeLisle as Moon Butterfly
- Jenny Slate as Pony Head
- Rider Strong as Tom Lucitor
- Alan Tudyk as River Butterfly
- Susana Ballesteros as Female Mariachi Member
- Jeff Bennett as Toasting Mewman
- Dominic Bisignano as Mewman Dad
- Greg Cipes as Tad, Mewman Boy
- Daron Nefcy as StarFan 13
- Gabriel Olivia as Male Mariachi Member
- Kari Wahlgren as Stump Merchant, Mewman Baby, Mewman Girl
- According to Star and Marco's Guide to Mastering Every Dimension, Stump Day (shown to be Mewni's equivalent to Christmas) is also Star's birthday, meaning she turns fifteen in this episode, followed by her fourteenth birthday in "Star Comes to Earth".
- For a brief moment, Star speaks Spanish (revealing that she is familiar with the language) with one of the musicians:
- ¿Lo que es un día de tocón? (What is Stump Day?)
- ¡Es un día muy importante! (It's a very important day!)
- This is the second holiday-themed episode of Star vs. the Forces of Evil, after the Halloween-themed episode "Hungry Larry".
- Star Butterfly's birthday is revealed in the series to fall on the same day as Stump Day. This was previously revealed in YouTube live chats hosted by Marco Diaz and StarFan13.
- Tad is revealed to still be living in Kelly's hair.
- Stump Day could possibly be the Mewman equivalent of Christmas.
- The episode and the legend it is about share many similarities with the mythical Krampus and the 2015 film based on it.
- Several initials on the Stump match the initials of some of the show's production staff:
- DN = Daron Nefcy
- SO = Sarah Oleksyk
- GG = Gina Gress