Do you celebrate Star Wars Day? Because your favorite superheroes from the Marvel Cinematic Universe apparently do, taking some time to joke around with their fellow franchise on Twitter.

Star Wars Day is an unofficial holiday among fans, celebrated every year on May 4. (“May the Fourth be with you.” Get it?) In recent years, Disney and Lucasfilm generally celebrate the day with special announcements or interactions with fans.

This year, the official Star Wars Twitter account asked: “We’re putting a crew together for #StarWarsDay. Don’t fly Solo. Who’s your co-pilot? #HanSolo.”

The question is clearly in reference to the upcoming Solo: A Star Wars Story, which will provide the backstory of Han Solo (played here by Alden Ehrenreich) and explain the origin of his friendship with his co-pilot, Chewbacca (Joonas Suotamo).

The various Marvel Twitter accounts responded in humorous ways.

  • “Can we have more than one co-pilot?” asked the official Avengers account, posting a picture of its very large cast.
  • “This rabbit makes for a worthy co-pilot,” said the Thor account, with a picture of the character in a spaceship with Rocket the raccoon.
  • “Real co-pilots. Not actual size,” said the account for Ant-Man and the Wasp, about two superheroes who can change their sizes.
  • “Co-pilot royalty. Wakanda forever,” said the Black Panther account, focusing on the royal siblings of T’Challa and Shuri.
  • “Co-pilots til the end of the line,” said the account for Captain America, in reference to the title character’s best friend, Bucky Barnes.

Both properties are owned by Disney, and they are two of the biggest film series in the world right now; as such, the two are something like friendly rivals. Star Wars: The Force Awakens had the biggest opening weekend ever until Avengers: Infinity War broke it last week, and both star Mark Hamill and Lucasfilm president Kathleen Kennedy were quick to congratulate the new victor.

Many other Disney-owned properties also chimed in, including The Incredibles (coming back to theaters for a sequel June 15), Christopher Robin and the Muppets. So basically, the Mouse House took a “holiday” dedicated to one of their big money-makers and used it to advertise a bunch of others. Clever trick.