"How are you?" To which you might reply, "I'm in great form, thanks." Can also be used in the sense, "He was in awfully bad form last night." ("He was bad humored last night.")
They're only saying goodbye, they're not actually wishing you any sort of luck at all.
And for a good introduction into the proper usage of words like "feck", "bollocks" and "arse" , check out the above clip of the classic Irish sitcom, "Fr. Ted."