The Eeveefree Forest
When eeveelution fems are in heat, the butt-sniff serves to both learn another's scent and increase sexual arousal. while the female doesn't have to sniff the male's butt and genitals, if she decides to do so she must do so before he does.
Leftovers
A rump sniff was considered a protected cultural practice. "no...!" she gasped, lowering her tail reflexively between her legs. the poor girl was shaking, but i couldn't leave well enough alone.
Succubus Sorority: Puppets
Play with your ass. sniff your soaking panties. let yourself slip away. cast yourself down the river of desire._ she made a needy groan.
The Jackal Awakens
Certainly, it had never been a mystery to _her_why dogs greeted one another with a polite butt-sniff. she, however, was far past polite - and the very next night, she took the final step, burying her tongue in his ass instead of her nose.
Misfortune Teller
Ashley tilted to the left, raised her leg, and let loose a loud 'pffrtt' straight from her ass. "sniff and be happy."
A Bolt Of Lightning
At the butt sniff, lighting jerked out off the porch and onto the grass, looking shocked at bolt and after he was done speaking, lightning barked loudly "what do you think you're doing?" "it's what normal dogs do," bolt said.