The Duke of Cambridge has admitted to the guilty secret of watching the show Pimp My Ride.
William's confession came as he and wife Kate visited the central London headquarters of youth charity XLP to learn about its work training mentors to help troubled young people.
The royal couple heard the stories of teenagers who have benefited from the programme after their lives were blighted by issues like knife crime, mental health problems and gang violence.
One former gang member Sephton Henry, who flourished after having a mentor and now uses his experiences to lecture police, teachers, probation officers and others about gang culture, gave a chilling account of his former life.
But in a lighter moment XLP (The eXceL Project) founder and chief executive officer Patrick Regan told the audience how the Cambridges had visited some of the charity's projects last year and saw the organisation's mobile recording studio set-up in a former police van.
The van was featured on the MTV show Pimp My Ride in 2008 and was transformed into the studio, proving a popular attraction with young people.
When the charity's founder asked "anyone seen the programme Pimp My Ride?" there was laughter and a number of people put their hands up, as did William who chuckled.
Mr Regan carried on joking, and said when he told staff William was making a return visit, he was asked: "Can you get him to rap in the van?"
When Mr Henry, 27, was asked to come forward he told the audience gathered at All Hallows-on-the-Wall: "I spent 18, 19 years homeless, sleeping on sofas, been in prison seven different times - I've been shot at, stabbed, been bricked, bottled, run over."
The former gang member, from Greenwich, south-east London, described the approach of his mentor, Ethan Bernard, 34, who joined him on stage: "Most people judge and punish instead of discipline and guide, Ethan showed me hope and didn't judge, showed you can actually change."
The mentor said about the young man he helped: "It was a challenge I really wanted to accept having gone through many of the similar issues."
During the event William and Kate, who wore a red outfit by bespoke label Eponine London, heard an original song, Heaven Help Me, by mentee Basia Bozzao, 20, from south-east London who talked movingly about her battle with mental health issues.
Afterwards they were presented with a CD of the song and Mr Regan told them he hoped to hear it "blasting out from Kensington Palace" and William quipped: "Do we get the van? I want the van."
Mr Regan, 42, set up XLP in 1996 after doing youth work in a school and seeing the issues young people face.
XLP now works in more than 75 schools in London helping young people who are facing emotional, behavioural and relationship challenges.
Its mentor programme sees at-risk 11 to 18-year-olds matched with a community mentor who commits to providing them with two hours face-to-face time each week for a minimum of 12 months.
More than 90% of beneficiaries have either remained in or returned to school and are doing well after a year with a mentor.
Mr Regan told the audience: "I remember meeting a kid who wore a bullet proof vest under his school uniform and he said 'I'll be dead by next week'.
"He got stabbed through the neck six weeks later. He survived. I met a 14-year-old girl who said her biggest aim in life was to be a single mum.
"So I found 17 people to give me £25 per month and I started XLP."
Miss Bozzao met William and Kate after her performance and commenting about their visit said: "It's so important, especially where mental health is concerned. It's such a taboo subject and the issues aren't talked about. They are so important and can raise much more awareness and hopefully help a lot of people.
"The fact that they wanted to come and the fact that they want to help mental health is incredible. It's the first time I have shared anything like that and then sung the song."