Google bomb

A Google bomb (also referred to as a 'link bomb') is Internet slang for a certain kind of attempt to influence the ranking of a given page in results returned by the Google search engine, often with humorous or political intentions. Because of the way that Google's algorithm works, a page will be ranked higher if the sites that link to that page use consistent anchor text. A Google bomb is created if a large number of sites link to the page in this manner. Google bomb is used both as a verb and a noun. The phrase "Google bombing" was introduced to the New Oxford American Dictionary in May 2005. Google bombing is closely related to spamdexing, the practice of deliberately modifying HTML pages to increase the chance of their being placed close to the beginning of search engine results, or to influence the category to which the page is assigned in a misleading or dishonest manner.

Life Cycle of a Bomb
A Google bomb begins as a webmaster prank. A website manager convinces fellow website managers to put on their sites a hyperlink to the target site containing the desired search words. If enough of those links appear in the various sites on the web, Google's algorithms will recognize that site as being a potential search result for those keywords. Eventually, the site may work its way to the top of the search results.
Google bombs often end their life by becoming too popular or well known: they typically end up being mentioned in multiple well-regarded websites, which themselves then knock the bomb off the top spot. Wikipedia, a notable example, has beaten many Google bombs to the top just by mentioning them in this and other articles.