EFSF stands for European Financial Stability Facility. Or so they say. I can only see it as standing for European Financial Science Fiction. How can it be anything else given the nature of the arrangement?
EFSF is basically a scheme whereby euro-area governments get together to bail out partners facing sovereign default. For this purpose, it issues bonds like any other organization in need of funding. Those bond issues are backed up by guarantees provided by participating governments. This is where the thing starts to look fictitious.
It is essentially an idea that aims to make things worse in order to make them better — for the guarantees that participating governments pledge themselves mean an additional burden on their already amply stretched public finances. The situation becomes even more surreal when one takes into account the fact that potential bailout targets are listed among the governments promising the guarantees. Thus we find ourselves in the realm of people eating themselves to keep themselves alive. This is highly fictional if not terribly scientific.