Chewing Orchestra

What is it with people who chew loudly? It's either that, or they speak while chewing... both make me lose my appetite and wanna smash that persons' mouth to pulp.
Don't they notice all the stares they receive as they happily make more noise than a construction goin on in the middle of Pudu?

See, the trick is, chew, swallow THEN speak.
Chewing, speaking and spitting is NOT the way.

It baffles me how they don't realise just how much noise they're making. Tell me, is simply because under some strange reason these people just cannot hear themselves chewing loudly? Or are they plain ignorant?
What is it!? Enlighten me please! Ohh and i know that you know at least one pest who does it. Do us all a favour, and just tell them off. They need to know.
You could also record it secretly, then tell them you have a sound clip of this nasty person chewing loudly. See if they get the hint then. If they're still clueless, say "THAT'S THE NOISE COMING OUT OF YOUR MOUTH MORON! YOURS! YES, YOUR GAP HOLE!"

Oh, wait you know what would also be fun? Imitate them! Yeah, that's it. Take a bite, and start chewing loudly, and then start talking at the same time. Try to get some of that food on their face too, if possible. That oughta show 'em. Hah!