What functions other than style does a vocal hiccup serve?

LGsing

MJ used it to express fear and excitement.

Diana Ross uses it.

Britney used it in her earlier work.

highmtn

None.  It's all about style.  A-heh!!!

LGsing

I also have it.

highmtn

It's something that you can use to add an accent. As long as you can avoid it when you don't want it to happen, and can do it when you DO want it to happen, it's all good. So the function of the glottal stroke is to decorate the spot in the song where it occurs. Use sparingly. A little bit goes a long way.
: ^)

LGsing

That's good to know.