The 22-year-old appeared on the BBC Radio 1 show, "Breakfast with Greg James" when she finally spilled the tea and personally apologized to William and Kate.
Radio host Greg James started to tell the story on air before Camila cut him off and jokingly said, "Don't tell anybody what my mother and I did."
James continued his story after laughing off her funny threat.
"We're in Kensington Palace for the teen heroes. We're about to meet William and Kate, and I said, 'You've got to steal something. Steal something!' And I said, 'Steal that pencil,'" the BBC radio host said.
Camila responded, "I was like, 'You triple doggy dare me?' ... And you can't not do a triple doggy dare. If there's anything I've learned in my life, it's that. So, I did it."
The pop star exclaimed that James actually ratted her out to a palace staffer.
"I was like, 'Oh, my God.' And I put it in my mom's purse, and my mom was like, 'No, we have to give it back. We have to give back the pencil.' And I was like, 'No, he triple doggy dared me. I have to take the pencil,'" she recalled. "So, I still have it. I'm sorry, William, and I'm sorry, Kate. I honestly couldn't sleep last night. I had to get it off my chest."
The Royal Response
It is hard to fly under the radar when you admit to stealing on the radio but it does not help when the radio station tweets William and Kate's official account.
"@KensingtonRoyal @GregJames may have got @Camila_Cabello into a bit of trouble at the Palace 👀," the station tweeted.
It did not take long for a response and the official twitter replied with a pair of emoji eyes. Many people thought the eyes emoji was the digital equivalent of an IRL eye roll while others thought it meant that they will be keeping a close watch on the singer.
Fans Dig It
Fans were ecstatic to see that the royals replied to Cabello's admission and let their voices be heard in the comments.
"Love this reply @KensingtonRoyal" one fan wrote while another said, "one of the best moment of my twitter existence ever."
Another follower joked about a serious punishment for the alleged crime, "May I make a suggestion William? Take her to @TowerOfLondon that should do the trick," the user commented.
One follower begged them for mercy and wrote, "Please don't put her in Jail.. she is releasing her album on December 6."
Why Was She At The Palace
Camila was at the palace to honor the 10 finalists of the BBC Radio 1 Teen Heroes Awards.
"I was so honored to be invited to Kensington Palace to meet and celebrate this year's Teen Hero finalists with the Duke and Duchess of Cambridge," Cabello told the BBC during the event. "Hearing the incredible things these Teen Heroes have done is so inspirational! Their passion and dedication to help others is amazing and they really blew me away!"
We hope she enjoyed her time at the royal palace because she may not be invited back after the pencil jacking.