What the F?

Yesterday John Kerry announced that the W. in George W. Bush stands for Wrong. What does the F. in John F. Kerry stand for? There was a radio show yesterday afternoon that asked listeners to call in with their opinion regarding the meaning of the W. and the F.

Here are a few examples of F.
Fake
Fluff
Fool
Failure

A couple of mine:
Foundationless
Fickle

My favorite, however, was a man who called in to say he just wish the F. in John Kerry would go away. (say it out loud)