He plays with it, causing it to go off.

In some of their kinkier fuck sessions over the years, Tom had been in a very similar position to this, in out of idle curiosity, played a little with Sarah’s asshole while he was fucking her doggy style. She’d always claimed to find it weird, but the way she’d blush while saying it made Tom think she was just afraid of admitting that she liked butt stuff at all.

Old habits die hard, so almost without thinking about it, Tom lightly caressed the scend gland with a finger. Immediately, Sarah shuddered with pleasure and moaned. “Oh, be careful...” but the tone of her voice made it pretty damn clear to Tom that she didn’t want him to stop in the slightest.

Still thrusting into her wet and furry sex, he started going further, putting more pressure on the new part on his wife’s body, until suddenly he’d gone a little too far. Sarah suddenly hissed, an animalistic sound that sounded out of place from any human, and suddenly liquid started spurting out of the gland, landing on Tom’s chest. It was pungent, to be sure, but didn’t smell like actual skunk spray. After all, part of the appeal to Tom of a skunk girl was being able to be sprayed, so he didn’t want to ruin that part of the fantasy. Instead, the spray smelled more like a heavy, floral perfume. But it did more than that, he’d also made sure the spray had another effect.