Josh Charles struggled to keep Taylor Swift music video cameo a secret

Josh Charles struggled to keep his surprise cameo in Taylor Swift's Fortnight music video a secret.

In the music video, which was released on Friday, Charles and Ethan Hawke, who played students Knox and Todd in the 1989 film Dead Poets Society, appeared as scientists who conduct experiments on the singer as she is strapped to a gurney.

The Good Wife actor posted a selfie with Hawke on Instagram and reflected on the secretive project.

"I don't like keeping secrets so that was hard. I didn't even tell my kids until the other day!" the father of two wrote on Instagram. "Here's a couple of tortured old poets about to board an early flight to be pop stars for a day. Been through a lot with this dude over the years, but safe to say this was a most memorable day.

"We were treated with such class by Taylor and her crew from beginning to end. What I'll remember most was the laughter. There was a lot of it. Like we were 17 all over again."

In the comments, Hawke replied, "Hell Yeah, Josh.... I think we should keep it rolling- like Maybe Todd & Knox start appearing mysteriously in the background of all the world's great poets!"

Fortnight, which features Post Malone, serves as the lead single from Swift's 11th studio album The Tortured Poets Department.

After releasing the video, the 34-year-old singer gave the actors a shout-out in an Instagram post.

"I'm still laughing from getting to work with the coolest guys on earth, @ethanhawke and @mrjoshcharles (tortured poets, meet your colleagues from down the hall, the dead poets)," she wrote.