Ok, since this is solved I can go ahead and say the obvious – use Illustrator or Indesign. Make the bubble, drag it over as a smart object, end of story.
Or this in PS.
1. Draw the balloon as a white area.
(start recording action here)
2. Layer effects - stroke
3. Make an empty new layer below the balloon.
4. Merge balloon layer with the empty layer.
5. Lock transparency for the layer
(end action here)
6. with a hard edged brush, cut white lines into the stroke. No need to worry about going over the lines since you locked transparency. No need to be mathematically accurate either, readers will understand it's a whisper.
This took me about 30 seconds without the action so when you have that, it should take about 20. Quick enough?
Ok, I was lazy and didn't make it balloony but it doesn't matter since the balloon area can be any shape you want.