Because we can hold water in our very hands, run with it, and not spill a single drop.

You know i realized this two months ago and told my officer...we lol'd about it. The answer is simple. Waldo the farting dog is inside each head of the zombies.

Their breath probably does consist of highly volatile dust particles that cause all manners of nasty atomic reactions. Or so is my own hypothesis. As to how they exhale it is a different matter entirely.

Going by generic lore zombies are in many cases the result of necromancy, a form of magic incantation or ritual that raises the deceased corpses to wander and in some cases be controlled by the caster. The arcane magic allows the undead bodies to function without the need for muscles and organs, as they are entirely, or almost entirely fuelled by magic power. Seeing as we have observed several instances of infernal rituals take place within the Clockworks, it would be safe to assume that they use a form of propulsion magic to scatter dust particles from their mouth, which presumably had gathered within their hollow skulls over time. Their breath could also be purely magic-based.

Another theory is that they are able to gain enough momentum when thrusting their head forward to release a stream of dust particles, although it does not explain how they can maintain a consistent stream over an extended period of time as they are known to be capable of.

I can't think of any other possible explanations at the moment, unfortunately. I am not a scientist after all.

Here is my hypothesis:

Zombies have been dead for countless generations, if not centuries or even milinea. During that time, their body has been sustained by tainted dark rituals (proven to exist thanks to Devilites trying to summon Trojan armies. Why did we stop them anyways? Trojans are nice to fight, give decent crowns and heal you after they die because they're obviously courteous gentlemen with manners, unlike most of the online people today), but even magic has a limit. (GASP! SHOCK! AMAZEMENT! STUFF!) Though their body has been, for the most part, remained intact, the dark magics have no use for organs and such, sustaining the undead body only with black magic. Thus, their organs have mostly decayed and exploded spontaneously into dust, which is pretty much what their whole body is stuffed with.

Now, at first the zombies were all "What do we do with this junk stuff?" Then they found out that if they stayed exposed to a certain theme (fire, shock, Nicholas Cage, etc.), their dusty insides would become tainted with the theme as well, which they would spit at nearby passers for fighting (and the lulz when they realize they're covered in zombie heart). The stun breath? Easy. Wouldn't you be a bit "ick" if you got sprayed by intestinal organs? And if you get set on fire by a breath (or get hit by Nicholas Cage), your main concern would be actually living. Do you know how much it costs to keep your costume and armor clean? Especially trudging through the old Clockworks, with mud and all that. Why, you whippersnappers, back in my age we had to walk 10 miles uphill to our biospheres, both ways!

/me waves a cane in the general direction of an audience.

Part of me believes that it's not so much magic as it is energy from the core, but magic is still a possibility. There's an audible inhale before they use their breath attack, so there's some sort of outcome when they fill their dusty lungs with air.

And Wavara, I think that's just our friendly potato sandwich that makes the forums entertaining. I'm just a boring angel with a few insights, and have a tendency to be exceedingly excited about the most mundane happenings.