A Pyroclastic Fart is named after 'pyroclastic density current'; a volcanic event of considerable destructive power.
A Pyroclastic Fart is characterised by several key factors. It is a fast moving jet of particles of varying size and superheated gas. Too dense to be supported by air; it rushes down ones legs and spreads out on the floor in a shock wave. It behaves like a fluid; with lethal effect.
A: "wow man, that was a seriously Wet One!"
B: "Worse than, it was a Pyroclastic Fart"
A: "Oh no..."
B: "yeah, its Pompeii all over again."