The woman accused of murdering Becky Watts said texts she exchanged with her boyfriend about kidnapping schoolgirls were “just extremely sarcastic”.
Shauna Hoare, who denies murder, told Bristol Crown Court messages sent to Nathan Matthews were “unfortunate”.
The 16-year-old’s remains were found in a shed in Bristol in March.
Ms Hoare’s boyfriend Mr Matthews has admitted killing and dismembering his stepsister, but denies murder and conspiracy to kidnap.
The prosecution’s William Mousley, QC, asked Miss Hoare if it was just an “unfortunate coincidence that you and Nathan were talking about kidnapping a girl and bringing her back to the house” in text messages months before Becky was killed.
Ms Hoare replied: “I don’t think it necessarily was a coincidence… It was just extremely unfortunate.”
She also told the court it was “bad timing” she showed Mr Matthews a parody video on YouTube called Do You Want to Hide a Body the day after Becky went missing.
The accused was asked if it “just happened” that she was not in the house when Becky was attacked, that she came inside from the garden just after Mr Matthews moved Becky’s body to the boot of his car, and that when the body was being dismembered she did not “see, hear or smell anything suspicious?”.
Ms Hoare agreed she was with Mr Matthews for most of the time over that period, but said there were explanations why DNA attributable to her had been found on two bags and a face mask found in the shed where Becky’s body parts were hidden because they had previously been in her house.
“You thought you could get away with it,” said Mr Mousley.
“I didn’t have anything to get away with,” Ms Hoare replied.
“Are you just very unlucky?,” Mr Mousley asked.
“Yes,” said Ms Hoare.
Earlier, Ms Hoare told the jury she had heard Mr Matthews using a circular saw for 15 to 20 minutes on Sunday 22 February, three days after she disappeared.
Responding to questions from Andrew Langdon QC, defending, she said she assumed her boyfriend was doing “a boring job” in the bathroom and “just left him to it.”
Ms Hoare also told the court it was a “complete shock” when she was arrested after the disappearance of Becky.
Mr Matthews, 28, of Hazelbury Drive, Warmley, south Gloucestershire, admits perverting the course of justice, preventing lawful burial and possessing a prohibited weapon.
Ms Hoare, 21, of Cotton Mill Lane, Bristol, denies murder and conspiracy to kidnap, a weapons charge, perverting the course of justice and preventing a burial.
Two other men, Donovan Demetrius, 29, and James Ireland, 23, deny assisting an offender.
The trial continues.
Read more: www.bbc.com