Speaking in a new featurette on the movie (via Entertainment Weekly), star Robbie went into some of the background of the character.
"Greta described Weird Barbie in the script as a cross between David Bowie and a hairless cat," she said. "It is so strangely accurate."
Gerwig added: "Weird Barbie is truly the Barbie you'd play with too much. You'd brush out her hair and then you decided you want to cut it, then you'd see what happens if you light it on fire and draw all over her face.
"You put her in the splits and try to change her clothes. I had this idea like, 'Well we have to have a Barbie that represents that fate of so many Barbies.' I wanted her to be funny and wise."
The director also praised McKinnon, whom she has known since she was a teenager, admitting: "I always thought she was most talented person I've ever met. It was really special when we were on set together. It was a very full-circle moment."
In other Barbie news, the hit movie is now available in the UK and US as a digital download, so fans can relive the magic all again on the small screen.
The film recently hit the milestone of biggest movie of the year after crossing $1.36 billion at the global box office, surpassing The Super Mario Bros Movie.
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