Intense oral on their thumbs, then titty fondling.

"Hmmm," Hannah said, smiling at her two laboratory subjects as she held them each by a hand. "We discovered through research that kissing is just too weird. So let's try something else." Her smile widened to a grin. She shifted her grip on Zack and Gavin's hands. "Stick your thumbs out," she said. "Okay."

She tugged on Zack's hand, raising it to her lips, and kissed the tip of his thumb. She turned her head and did the same with Gavin's hand. Another kiss. Another sigh of warm breath from her nostrils. She went deeper for her next trip, sucking in the pad of Zack's thumb, licking it from bottom to top. Then Gavin's.

"Uhhh, whoa," Gavin said. He felt a tingle ripple through his body as Hannah gave his thumb a close impersonation of a blowjob. His cock twitched. "I, um. Does this count as oral sex?"

Hannah chuckled in her throat as she sucked on Gavin's thumb. She nibbled, digging her teeth in just a little, and attacked again with her tongue.

"Whoa, wow," Gavin said. His cock twitched and the head swelled.

Hannah let Gavin's thumb slip out of her mouth. "I'll take that as a yes," she said. "Your turn, Zack."

Zack closed his eyes and enjoyed Hannah's sensuous oral treatment of ... his thumb. What a tease. But it felt good. Why, with the right rhythm, a touch that was gentle, but firm, insistent...you could make out with someone if you could touch them almost anywhere. Images spun in his mind. Handing Victoria a book. Giving Heather a mug of coffee. And a finger lightly caressing the back of the hand, touching the wrist, a promise and invitation for more.

Hannah went back and forth two more times. "Mmm, looks like this is really working for you, Gavin," she said.

Zack couldn't help but look. Gavin's penis was fully erect, the veins standing out, the tip weeping. From a thumb job. He glanced at Hannah's nakedness, her nearness, feeling the memory of her pussy, hot and slick on his covered cock.

Hannah added, "I guess you need a little eye candy, Zack." She appraised him. "Or something a little more exciting."

Hannah brought their hands together, touching their wet thumbs pad to pad, stroking them with each other. Gavin trembled at her side. Zack's breath deepened. Hannah lifted their thumbs to her lips and sucked them in together.

Now it was Zack's turn to say "Whoa!"

Hannah worked on Zack's and Gavin's thumbs together, licking, nibbling, sighing eagerly and stroking her lips up and down their thumbs like she was giving them a double blowjob.

Zack didn't doubt she'd be pleased to do exactly that. But him and Gavin together, well, he was hung pretty good, and Gavin, well, he'd only seen Gavin pissing, but erect, he had Zack beat. So maybe thumbs was as far as it was going to go.

On Hannah's other side, Gavin was sighing vocally like Hannah was really going to town on his dick. Hannah rubbed Zack and Gavin's thumbs together and sucked hard, bringing a moan out from Zack.

Zack thought, Hannah fucking Woodsen, Sex Goddess, is doing a blowjob on my thumb. And it's working. He felt his cock twitch as Hannah kept sucking and rubbing Zack's thumb and Gavin's together. Hella kinky. And Hannah the Mad Scientist has barely gotten started.

Hannah tilted her head back up and took a deep breath. She eyeballed the stiff indicators she used to measure her efforts. Each young man raised a firm erection, pulsing with his heartbeat, Gavin's throbbing more rapidly than Zack's.

"Mmmm, looks like that worked," Hannah said. "Now, boys, let's try a new experiment. Nothing big." She moved Gavin and Zack's hands back to their sides and let them go. "Hold on a minute." Hannah reached round for the bottle of lubricant Gavin had been using when he jacked off to the spy video of Zack and Hannah fucking.

Hannah opened the squeeze bottle and held it out over Gavin's erect penis. "Slick yourself up," she said. Gavin held out his palm and Hannah squirted on a generous pool of lube. "That's the way. Now you, Zack." Zack followed Gavin's example. "Okay, that's good, stop. Give me your hands."

"Um," Gavin said.

"The safeword is safeword," Hannah said. "Say that and we stop and give you space."

"Okay," Gavin said.

"Okay Zack?" Hannah asked.

"Yeah, okay," Zack said.

Hannah put her palms on the back of Zack and Gavin's hands and lifted them onto her bare breasts, pressing their lubricated palms and fingers to her skin. "Oooh, that's good." she said. "Your turn to work on me."

Hannah coached Zack and Gavin in how to touch her breasts, how much squeezing felt good, how to stroke their lubricated thumbs over her nipples. Hannah's breaths grew deeper and faster as Zack and Gavin's touch grew more sure. Her nipples hardened under the strumming of their thumbs. Her chest began to flush pink.

"Safeword!" Hannah called out.

Zack and Gavin froze, then took their hands away, Zack first, then Gavin after a moment.

Hannah was panting raggedly. "Good. Uh, good job," she said. "You guys were really good. Sorry I had to safeword. I wasn't ready to come yet."

"You were going to...?" Gavin said. "Just from, um, your breasts?"

"Yeah," Hannah said. "My titties are pretty sensitive sometimes. Made cheerleading hell if my bra wasn't fitted just right on one of those days."

"Oh," Gavin said. He looked at Zack, then back at Hannah. "So what's next?"

Hannah chuckled in her evil, mad-scientist tone. "Well, funny you should ask."