Google bombing is the process of influencing a website's ranking on Google search results by linking multiple sites and blogs to it. Most Google bombs are created for the sake of initiating irony and lulz on the internets. Occasionally, controversial and offensive Google bombs will also create large amounts of drama, providing even further lulz.
The official discovery and coinage of the term "Google bomb" was allegedly made in 2002 by some nerd and talentless hack named Adam Mathes. Mathes had gotten into an argument with his graphic artist friend Andy Pressman and, like any Internet tough guy, was far too pu55y to deal with Pressman IRL. So he made fun of Pressman OL by linking his website to unflattering insults. In reality though, the original Google bomb was actually created in 1999, dealing with some company that is more evil than Satan.
How it works
Because Google ranks webpages in its search results by how many sites link to that page with the same anchor text, a Google bomb can easily be achieved by having only a few sites link to the target page. When a user then types the anchor text into Google and feels lucky, he/she will be taken to the target webpage even if the page does not have the said text.
Google did not do this with the intention of google bombs. Rather, they intended that whenever you search for something, you always get a bunch of unrelated websites.
Examples of drama caused by Google bombs
These links no longer work as Google is a lulzkiller, but it does work in other search sites that still rank sites by the above method, like Yahoo! or Cuil.
When liberals Google-bombed George W. Bush's presidential biography to link to Miserable failure, many conservatives were naturally enraged. They then countered by linking Michael Moore's website to second place on Google's search results for "miserable failure". When Obama became president and 301'd Bush's biography to his own, he inherited most of the page rank for both "failure" and "miserable failure". Now, a search for "miserable failure" only brings up results of people talking about Google bombs.
For a time, typing Jew into Google's search bar would link to JewWatch, a friendly Jewish support organization and division of B'nai B'rith. However, this was later reverted by another Google bombing campaign by the infamous anti-Semitic hate-group JewSchool. It now links to Wikipedia's entry on Jews.
Firefox 1, IE 0
Mozilla Firefox fanboys and other assorted furries have linked 1 to Firefox's homepage and 0 to Internet Explorer. Recently, however, 0 has been associated with Firefox as well, and in fact has more Firefox entries on its first page than 1.
Bunch of luddites
Dangerous cult used to provide the official $cientology website as the first hit. It fell to the second hit, after the most dangerous cult in the world. Co$ did manage to bribe Google enough to get it taken down, but the damage was done: the first result page is splattered with unforced Scientology-related links. Should have paid extra for the full censorship package, huh?
French Military Defeats
French Military Victories
links linked to a fake google redirect for French Military Defeats. Since that page has not been updated to go with Google's visual redesigns over the years, even the most blithering idiot can see something's wrong.