I suppose, as you overheard it, you couldn't supply more context? Without it, I can think of only two possibilities (and neither of them is very convincing!)
'Fortunately I fell off the bar'. Not very likely, but it may have been fortunate to fall off something, if something worse would have happened if you hadn't fallen off it.
'Fortunately I felt off par'. Feeling 'off par' (not particularly well) isn't usually fortunate, but the person you overheard may have had a lucky escape from some social occasion that she wouldn't have enjoyed.
Student or Learner