A metaphor to describe an entity that exists only for its own benefit. A quick web search seems to show this phrase is commonly used by policy wonks and pundits to describe government institutions. In his article "The Intelligence Gap: How the digital age left our spies out in the cold"1, Seymour M. Hersh wrote this about the NSA: "One former official described the civilian leadership as 'a self-licking ice-cream cone', with little tolerance for dissent or information it did not wish to hear."

1The New Yorker, December 6, 1999, pp. 58-76.