airplane ass 

This describes the phenomenon that people sitting in a plane will get smellier and more repulwsive than people doing a similar amount of sitting at home or at work. Regardless of how short or long your flight is, merely being seated in an airplane means your ass will stink, for several reasons.

Firstly the air pressure differential after take off means that air pockets of intestinal gas will be higher pressure and more likely to force themselves out of your chocolate barking spider.

Secondly, consider the smell of every other traveller that has sat in the same seat, warming the same cushion with the same intestinal gases and sweat, and dealing with the everpresent background noise and stress of air travel, while a crappy movie plays on a screen too small to see and which is blocked anyway by other passengers getting up, sitting down, or just hanging like douchebag fuckwits in the aisle talking to their colleagues because they think that air travel is FUN.

Meanwhile the stewardesses are busy standing in the rear gantry leaning against the snack boxes (which now cost $5 extra each just to buy) with their legs open and their panties around one ankle getting shagged from behind by the stewards, and the pilots are busy smoking weed as the airport handlers break the locks on your luggage down below to steal your souvenirs and computers, under broad security rights bestowed by the TSA federal agency while the lone fat greasy headed steward who can't get any female flight attendant to part her Pink Sea for him is taking out his frustrations by forcing people to move out of Economy-Plus seating (which costs you $75 more at the check-in counter than regular Economy for an extra 5 cm. of legroom) regardless of the fact that once the plane takes off the people will just fucking move back in because airport security can't board a moving plane, fuckwits.

This combination of low air pressure, substandard treatment, and superstandard psychological pressure results in larger than usual pockets of intestinal gas forcing themselves out of your anus and warming the fabric around your fundament.

This also means that ANY TIME A PASSENGER GETS OUT OF THEIR SEAT, their ass comes up to the same level as the seated passengers' faces. This is especially notable when the first over-caffeinated passenger jumps out of his seat at the end of a flight to grab his carry on luggage so he can be the first to wait in a completely stationary line to disembark, and you're still seated, and his ass wafts a foul stench your way that makes your eyes water.

Possibly a contributing factor to air rage.

16-B: What do you think of that chick in 14-D?
16-C: Hmm. Looks kinda tired.
16-B: She's got a sweet ass. And I think I saw her get into the toilets with a pink dildo. I think I'm gonna jerk off on her face.
16-C: Yeah, but she walked past me just now and I got a faceful of grade-A fetid rancid eyewatering airplane ass.
16-B: Eurgh. Okay. Never mind. (goes back to doing crossword puzzle)

airplane ass by HMB January 13, 2007