Blowing into your partner's asshole, then sucking the hot air out as they fart in your mouth. A prelude to shit-eating.
Susan: Suck my ass, baby.
Joyce: Mmmm, so sweet honey.
Susan: Felch my shithole baby.
Susan: Open my ass with your tongue and then blow blow into my ass, hard!
Joyce: Fuck, I love this.
Susan: Suck my ass while I fart in your mouth.