So Julia Roberts was one of the latest celebrities to swan onstage during one of Taylor Swift's 1989 gigs a few weeks back - and it was just as impromptu as the photos would suggest...

Speaking of being hauled onstage with Swift, the actress said she had just slung on some leggings to bring her kids (twins Phinnaeus and Hazel, 10, and Henry, 8) to their first concert at Santa Clara’s Levi's Stadium. Naturally, when hearing there was an Oscar winning actress in the audience, Taylor had a meet and greet with Julia's kids and had this request of her own.

According to Vanity Fair, Swift said, "'Would you mind coming on stage during the song and dancing?'" Roberts remembered. Unsure of what to do, the actress says she consulted with her children, asking them, “What do you think?” 'Oh, Mom you have to do it!,' Robert said, echoing her children’s response. “My youngest son said, 'Only do it if you want to, Mommy.' It was so sweet!"

Of her moment with Joan Baez and Swift, she said: “I was so nervous! It was one of those crazy out-of-body moments. I can't tell you anything that happened from the moment I came on stage."

Asked if she had any inkling at all if she was going to be asked onstage, she added, “I would have washed my hair... I was, like, wearing a ponytail and leggings, tennis shoes."

In other Taylor related news, you'll be happy to hear that she calls Calvin Harris by his real name, Adam. Yep, things are that serious.