Star walks around school with everyone greeting her. She then comes across a group of students where Brittney is handing them out invitations to her birthday party. Star, who loves birthdays and parties, wants one. Brittney rudely tells her she can be invited only when pigs fly. So Star makes a flying pig, thinking that she is now invited.
Later that night, Star brings Marco along, but Marco doesn’t think they can go. As Brittney's Party Bus passes by, Star launches both of them onto the bus, much to Brittney’s annoyance. Marco nearly gets car sick, but stops himself when he sees Jackie. When Star sees how unhappy the guests are, she decides to liven the party with her spells. She turns the interior of the bus into a bounce house and creates a hot tub on the roof while Marco tries hard to hold his vomit.
When Brittney has the bus pulled over to kick Star out, Ludo attacks. Star fights his henchmen while Ludo and Brittney bound over their hatred for Star. When Star notices they are heading straight for a portal of Ludo's world, she tells Marco to take the wheel and they crash the bust right next to a bus stop. The Monsters come out hurt and Marco finally vomits into a nearby trashcan, along with Ludo. While Brittney thought her party was a disaster, her guests thought it was a huge success.
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Alan Tudyk as Ludo
- Minae Noji as Brittney Wong
- Grey DeLisle as Jackie-Lynn Thomas
- Daron Nefcy as Sabrina Backintosh/StarFan13
- Jeff Bennett as Justin
- The promotional poster featured a different title, "Party Bus", instead of it being the original title.
- Brittney is revealed to be a terrible singer in this episode.
- It is revealed that Marco gets motion sickness in this episode.
- Star's backpack in this episode looks similar to the infamous Spiny Shell (also known as Blue Shell) item from the Mario Kart games (specifically starting in Mario Kart 64).
- This is the last episode to be animated by Mercury Filmworks.
- May 3, 2015 (Canada)
- May 14, 2015 (United Kingdom and Ireland)
- July 30, 2015 (Germany)
- August 10, 2015 (Australia)
- September 6, 2015 (Israel)
- October 9, 2015 (Turkey)
- October 23, 2015 (Poland)
- November 5, 2015 (Spain)
- December 6, 2015 (Southeast Asia)
- January 29, 2016 (Japan)