Sarah Ferguson was left irritated as the crowd spoke over her at the amfAR charity gala at Cannes Film Festival.
The 64-year-old philanthropist and author - who was married to Prince Andrew, also 64 - was a special guest at the bash on May 23, and was there to shine a light on the genius scientists behind AIDS research and HIV prevention.
A painting of the late Queen Elizabeth II - Sarah's former mother-in-law - was auctioned off for more than £400,000 for the cause, but Sarah was forced to call out the rowdy guests and accused them of just being there to "party" and not to applaud their outstanding work.
In a clip from the event shared on social media by model Heidi Klum, Sarah, Duchess of York told them to "stop, stop, stop" and pay attention, but they were having none of it.
She fumed: "Quiet because the incredible person Simon de Pury has done an amazing job tonight, this is exceptional, and all I want to say to everyone in this room is stop, stop, stop.
"Did you see I removed the microphone because all of you are saying 'I want to go, because where is the next party? What are we meant to be doing next?' But what I want to say is why are we here? What is the future and why are we not making our planet better for the youth of tomorrow?"
Sarah then said : "I am so sorry that we have completely destroyed your planet, but thanks to amfAR and these people with scientific brilliance..."
Earlier on in the day, she spoke about the importance of “family unity” when asked how she has helped support King Charles, 75, and Catherine, Princess of Wales, 42, through their cancer treatments.
Sarah - who herself had a double cancer scare but go the "all-clear" - told PEOPLE: "I think family unity is key... I think the key to life is that we all support each other. And also, forgiveness is a great thing. I think forgiveness of yourself, and forgiveness of others."
