A search engine aimed at children, which blocks many common search terms including the words menstruation and balls, has gone viral.
Kiddle was registered in 2014 and is powered by Google safe search but has no connection with the tech giant.
Other words blocked by the site include lesbian and gay, a decision which has angered the campaign group Stonewall.
Kiddle says search results are "handpicked and checked" by its editors.
Other apparent search anomalies include the blocking of the term circumcision but not of FGM (female genital mutilation), suicide but not self-harm, the actress Pamela Anderson but not Fifty Shades of Grey.
Kiddle's parent company is not named on the website but one of its early testers blogged that it was set up by the Russian founder of a site called Freaking News.
A form on the site invites users to submit suggested additional key words for blocking.
Lesbian, gay, bisexual and transgender terms also yield no results because the site "cannot guarantee the safety" of such searches.
"Young people regularly use the internet to find information on LGBT issues," a Stonewall spokesperson said.
"Attempting to stop young people finding safe and age-appropriate content of this nature will force many young lesbian, gay, bi and trans people to seek it elsewhere. This can take individuals down inappropriate avenues which might put them at risk.
"Kiddle should rethink its approach to blocking valuable LGBT advice and information."
Kiddle told the BBC it had received complaints "from parents and teachers" before the terms were blocked during early tests.
"Most LGBT sites have forums and user generated content. Even one picture of a half naked man posted as an avatar on such sites (after the site has been vetted) is enough to turn away most parents," the firm said.
It added that it had blocked the term "sex education" because of the illustrations contained within many sites hosting such material.
"What is OK for a child of 12 may not be OK for a child of five," it said.
"Since Kiddle results are either handpicked and checked by our editors or filtered by Google safe search, you know you get kid-oriented results without any explicit content. In case some bad words are present in a search query, our guard robot will block the search," Kiddle states on its website.
The site adds that its server logs are deleted every 24 hours and no user data is stored.
- 17 February 2016
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