<abbr title="Fat Finger Syndrome">FFS</abbr>
This also helps reduce ambiguity about the meaning of an acronym, improving the communication of semantic intent.
That said, it appears that expansion of <abbr> isn't consistently supported[1].
I suspect most screenreaders would simply say "Eff Eff Ess".
[1] http://www.powermapper.com/tests/screen-readers/labelling/ac...