Robbie Williams lost his virginity while wearing his school uniform.
The 37-year-old star - who is now married to actress Ayda Field - was first intimate with a girl while he was attending the St. Margaret Ward Roman Catholic School in Tunstall, Stoke-on-Trent, West Midlands.
He said: "I was wearing a blazer, tie, shirt and a pair of Farah slacks. It wasn't a court appearance. We had to go to school in uniform."
In an unusual interview on Robbie's Rudebox radio station, the Take That singer also asked his mother-in-law Gwen what she wore when she had her first sexual encounter.
She said: "A night shirt. A night gown. And a smile."
Speaking to Ayda, Robbie - who has previously admitted he struggles to stay slim - also revealed he wouldn't mind if she put on weight.
He said: "I would love you all the same, but I know you wouldn't be happy."
Ayda responded: "Do I put the donut down now?"
Robbie recently revealed he wanted to start having babies in the near future, possibly in 2012.
He said: "Ayda wants a football team. I want two. A boy and a girl.
"[We're going to call them] Woody and Sonny! Cool, eh? She wants to get on it now, but, I just got back off tour. There's a stretch from now until Christmas and then, we'll do some practicing."