Lily Allen once embarrassed her elder sister by encouraging Gwyneth Paltrow to walk in on her during a romantic clinch.
The Smile singer's moviemaker mother, Alison Owen, was close friends with the Hollywood actress when Allen was a child, and often invited Paltrow to the family home.
And Allen once took the opportunity to play a prank on her sister, Sarah, when she was enjoying a romantic moment with her boyfriend.
Owen tells Britain's Vogue magazine, "I remember when Lily was 11, Gwyneth came over to our house for a barbecue.
"Lily, being a naughty pixie, said, 'Come round and see the house', and she took her straight to her eldest sister's bedroom - who happened to be having a shag (sex) with her then boyfriend.
"The boyfriend was horrified, but Gwyneth burst into fits of laughter, and literally stayed laughing for five minutes."