A replacement for asshole in scat and shitplay communities, to specify excrement extruding or surrounding an asshole, while also not coming across as direct as specifying it.
When your partner spreads their asscheeks revealing their dark gaping asshole as you light a cigarette, take a puff and put the ashes inside your partner’s asshole , after putting the ashes, your partner closes up their asshole like a vent, and you repeat the process until the cigarette is finished.
Chad: Dude, Stacy came over last night, she let me do a black hole vent on her, it was so hot.