Key FOBs

So my mother got me this very lovely "Key FOB' from Coach for my birthday. One question - why are they called "FOBs"? I've asked the people at Coach and they said 'it's just the name'. I feel like FOB must stand for something. I've tried googling. Does anyone know the origin of this term?

(Editor's sidenote: No, this was not an attempt to alienate all two of my male readers, if they even still exist....)