We don't have to think too hard: "These variables define terms and websites relating to the TAILs (The Amnesic Incognito Live System) software program, a comsec mechanism advocated by extremists on extremist forums...this fingerprint identifies users searching for the TAILs (The Amnesic Incognito Live System) software program, viewing documents relating to TAILs, or viewing websites that detail TAILs." [1] Google said they stopped this with encryption, but even if true, and they have no gagged NSLs or just spies, your DNS and internet traffic still show connections to Tails website, directory servers, etc.

[1] https://www.theregister.co.uk/2014/07/03/nsa_xkeyscore_stasi...