When two or more individuals expel flatulence with a wretched order and they combine within a close proximity of each other, creating the perfect storm of stench.
On the ride home the next morning from the bachelor party, that included copious amounts of beer and tacos at 2 am, two anonymous passengers busted ass at the same time, creating a PooNado that reeked havoc on everyone in the car, causing the driver to pull over so they could seek refuge.
1. The utterly foul and disgusting blanket of odor that seems to follow someone out of the bathroom and rips down the hall after performing excessive amounts of defecation in the bathroom. Like a tornado, its measured on the Fujita Scale.
1. After walking out of the bathroom and not closing the door, Davin completely unleashed an F5 PooNado on the entire office.