Children as young as 13 are being advised that they can flout the age of sexual consent by a sordid NHS website.
The service, which is partly funded by EU and publicised in schools, even offers tips on sex acts.
In total defiance of the law, it advises that while sex under the age of 16 is illegal 'you are the only one who knows when you are ready'.
MPs and family groups say the service, which costs 56,000 pounds and is inspired by Dutch sex education techniques, should be halted because it encourages sexual experimentation among children.
The Respect Yourself website and smartphone app is the first service of its kind in the UK and has just been rolled out across 39 secondary schools in Coventry and Warwickshire.
The site contains sexually explicit images, diagrams of erogenous zones, a "sextionary" of explicit terms and advises that "there is very little stopping you accessing hardcore pornography from the comfort of your sofa."
It also discusses prostitution, the effectiveness of the morning after pill and suggests how children can get hold of sex toys despite being under age.
Meanwhile, the site's 'experts' suggest that young children might want to put off speaking to their parents about sex in case the subject upsets the parents.
In a question and answer section, experts commissioned by the NHS answer questions about sexual practices. Children as young as 13 are told masturbation will make them feel 'de-stressed' and have a stronger immune system.
Prostitution is described as 'technically legal' along with the explanation that 'people have sex for many different reasons, prostitution is one of them'.
A gallery of images of male and female genitals is featured on the website and the users are encouraged to take a quiz that poses multiple-choice questions to assess whether they are ready to lose their virginity.
A few words in the sextionary include Amaurophilia - a fetish when someone gets turned on by blindfolding their partner, Axillism - sexual act where a man rubs his penis under his partner's armpit, Blue Waffles - a slang term for nasty looking genitals infected with a host of different sexually transmitted infections, Eproctolagnia - a fetish when you are turned on by people farting, Gouch/Gooch - the sensitive spot also known as the perineum and Tribbing - sexual act where two women rub or grind their genitals against each other for mutual stimulation.
Incredibly, on bestiality, the advice is that while 'sex with animals is illegal, fantasising is not'.
"Parents will be appalled health professionals have supported the development of a resource that condones sexual experimentation by young people and uses crude and sometimes even foul language," the Daily Mail quoted Norman Wells, spokesman for the Family Education Trust, as saying.
"It merely encourages an unhealthy obsession with physical acts and will do nothing to help young people build healthy relationships or prepare them for a stable and fulfilling marriage in the future," Wells added.
The website and app were funded with 24,000 pounds from the NHS and 32,500 pounds from the European Union's Leonardo da Vinci programme.