Brown air is the kind of rectal expulsion that often causes symptoms similar to those experienced by mustard gas victims. An acrid, thick, almost tangible odour.
"Goodness me, Ponsonby just snuck out as I walked in only to be assailed by a cloud of the foulest brown air!"
"Yes, he's a bastard is Ponsonby. Notorious for his obnoxious air biscuits"
While staying at a friend's house, bringing a chic home ,hitting itdoggie style and sticking it in a girls butt without her permission, usually on an air matress.