Warner Bros.

Superhero movies have been taking themselves far too seriously for far too long, and the upcoming DC spinoff flick "Birds of Prey (And the Fantabulous Emancipation of One Harley Quinn)" is here to change that. And obviously, that starts with the film's very title.

Star Margot Robbie, who's set to reprise her "Suicide Squad" role as Harley in the new film, chatted with Jimmy Fallon on "The Tonight Show" on Monday, and revealed the thinking behind the moniker. The title is so odd, in fact, that when Robbie first unveiled it on her Instagram page last month, some fans didn't think it was real.

Fallon dubbed it "a mouthful," and Robbie concurred. But that was kind of the point, according to the actress.

"It's not a very serious movie, so we thought the title should reflect that," Robbie explained. "Like, 'Birds of Prey' makes it sound very serious, and [the subtitle is] kind of like Harley adding her, like, 'Hey, don't worry. I'm in this too.'"

Also in Harley's titular girl gang are Huntress (Mary Elizabeth Winstead),  Black Canary (Jurnee Smollett-Bell), Renee Montoya (Rosie Perez), and Cassandra Cain (newcomer Ella Jay Basco). Ewan McGregor plays the villain, Black Mask.

"Birds of Prey" begins filming in early 2019. The fantabulous feature is due to fly into theaters on February 7, 2020.