Unflappable

One word which has been brandished a lot during this election cycle is "unflappable." I have to admit that I had never heard of this word until this year, but given the context that it is always in, it obviously means "difficult to upset."

So does that mean that if someone is flappable that they upset easily? And if I am upset am I flapping?

"Boy, did I ever flap last night when that guy tried to pick up my girlfriend! I don't mean to be so flappable, but you'd flap too, if it happened to you!"

Or is it one of those words like "ingrate" where you can't undo the negation? I mean, you don't call a grateful person a "grate", now do you? You might think he or she is "great", but that's a different affair, entirely. And now that I think of if, "to grate" has nothing to do with gratitude whatsoever. Which is interesting, because being grateful should mean that you are full of grate, but how can you be full of a frame of metal bars?

ARGH! It's so frustrating!!!!!!

Uh, sorry to flap like that. Now where was I?