Dame Joan Collins has warned that Madonna's sons might get teased after the pop star bared her derriere at the Met Gala.
The actress, 82, recalled how embarrassed her son was after she appeared in lingerie in her film The Stud, and said Madonna's children might feel the same way after their mother arrived at the fashionable event in a bottom and breast-baring Givenchy ensemble.
Asked what she thought of the photographs of the 57-year-old pop star on ITV's Good Morning Britain, Dame Joan said: "I thought it was a costume party or a Halloween look, but it's the Met Ball, which is supposed to be one of the most glamorous and fashionable events, and I thought the bottom coming out was a bit over the top."
She added: "It reminded me of the time when I was in a movie called The Stud and pictures of me came out, and I was wearing a basque and stockings, and when I went to my son Sacha's school to meet the headmaster when he was 16, he was very embarrassed.
"All the boys were peeping around the corner, they had seen The Stud even though they weren't supposed to, and he told me later it was very embarrassing for him to see me in the basque.
"I said, 'but I covered up, it's not like I was naked', but his friends at school teased him unrelentingly. So Madonna's son also might get teased.
"I am the least ageist person, you do what you want to do. But if you want to do that, be prepared to be made a figure of fun, because I don't know anybody who hasn't been laughing about it."
Madonna has four children - daughter Lourdes with Carlos Leon and son Rocco with Guy Ritchie, as well as adopted daughter Mercy James and son David Banda.
Dame Joan also opened up about how difficult it has been to deal with the loss of her sister Jackie.
The novelist died of breast cancer in Los Angeles in 2015 and Dame Joan said she found it hard to stay in the city with her husband Percy afterwards.
She said: "It's very hard. When she first died I said to Percy, 'I don't think I can live in California any more, and we have to sell our apartment and go to Miami or somewhere'. It's very hard on us and my brother and the girls but we have wonderful memories of her, we have pictures of her all over the house.
"She was a great, lovable person. She was very shy, which people didn't know about her, and she had very close-knit friends and although she seemed very gregarious and outgoing when she was talking about her books, she was very shy."