A man who pretended to be a teenager on Snapchat to convince more than 150 children to send him sexually explicit videos and images has been told he's "every parent's worst nightmare" as he was jailed for 25 years. Judge Shaun Smith KC told convicted rapist Siah Riley he had never come across such a prolific offender of his kind throughout his 46 years in the legal profession. The 36-year-old defendant masqueraded as teenagers by setting up fake social media profiles, luring girls as young as