“TrackMeNot is a lightweight browser extension that helps protect web searchers from surveillance and data-profiling by search engines. It does so not by means of concealment or encryption (i.e. covering one’s tracks), but instead, paradoxically, by the opposite strategy: noise and obfuscation. [...] background process that periodically issues randomized search-queries to popular search engines, e.g., AOL, Yahoo!, Google, and Bing. It hides users’ actual search trails in a cloud of ’ghost’ queries, significantly increasing the difficulty of aggregating such data into accurate or identifying user profiles.”
▻http://www.cs.nyu.edu/trackmenot
Note that many network protocols have provisions to add random noise to defeat some types of privacy attacks but they are not always activated.