Plot: Whether it is 10-year-olds talking about who they have snogged or schoolgirls calling themselves sluts on their social-networking profile pages, it seems our kids can't get away from sex. But what happens when the banter and name-calling gets physical? Jeremy Vine reveals the problem of sexual bullying in our schools and hears from experts, parents and teachers - but most importantly from the kids themselves - on what we can do to tackle it