The Streisand effect is the phenomenon whereby an attempt to hide, remove or censor a piece of information has the unintended consequence of publicizing the information more widely, usually facilitated by the Internet.
It is named after American entertainer Barbra Streisand, whose attempt in 2003 to suppress photographs of her residence inadvertently generated further publicity. Similar attempts have been made, for example, in cease-and-desist letters, to suppress numbers, files and websites. Instead of being suppressed, the information receives extensive publicity and media extensions such as videos and spoof songs, often being widely mirrored across the Internet or distributed on file-sharing networks.
Example - In June 2012, Argyll and Bute council banned a nine-year-old primary school pupil from updating her blog, NeverSeconds, with photos of lunchtime meals served in the school's canteen. The blog, which was already popular, started receiving an immense number of views due to the international media furor that followed the ban. Within days, the council reversed its decision under immense public pressure and scrutiny. After the reversal of the ban, the blog became more popular than it was before.
See more examples at http://en.wikipedia.org/wiki/Streisand_effect