David Beckham -- I Diddled Myself in front of My Teammates

David Beckham claims he was the victim of a bizarre hazing ritual as a young professional soccer player ... in which he had to touch himself sexually in front of his male teammates.

It happened in 1991 -- when Beckham was just 16 -- and he says he had to stare at a photo of a famous Welsh soccer player named Clayton Blackmore and (more or less) masturbate in front of his teammates.

He said, "Everyone had an initiation that you had to go through on the youth team, that was one of the most uncomfortable ones."

He added, "I was embarrassed when I was saying it on camera let alone talking about it more. But it’s something that we all had to go through. It was definitely something I wouldn’t like to go through again!"