Please forgive me if any of the scientific jargon is erroneous. This is in no way an error of the infallible Mr. Spock, but of the author's highly advanced Wikipedia research methods.
"Excuse me, commander," it was mostly about the dare she assured herself as he completed a step several paces ahead of her.
Though, she conceded as he turned and said with a tilt of the head and a raise of eyebrows, "Lieutenant?", that it was equally for the pleasure of watching him do what he perhaps did best.
She passed him at a brisk walk, containing an amused tone and forcing a typically severe and confused expression. "If I may, I would pose a scientific query."
He fell into stride next to her, arms crossed behind his back. "Oh?" She glanced up briefly and the corners of her mouth twitched. "I shall of course reply with my utmost ability."
"Thank you, commander," they turned a corner past rows of sliding doors.
He glanced down and forward, anticipating extrapolation. "Hm."
She stared fixedly forward, maintaining a fairly rapid pace. They swerved once more, passing a mass of red with touches of blue.
"And of what nature is your question?" he prompted; she failed to control a sly smile.
"Anatomical, sir," she slowed as a final turn was made and stopped casually in an unoccupied stretch of hallway, facing him as she continued, "I've recently become aware of how acutely uninformed I am on the matter of lips." Composure back in place, an internally amused expression met a neutrally attending visage as his eyebrows rose in unison with computation of the inquiry.
"Ah, the lips. Labia oris, to be precise. I believe the definition that would most aptly serve you is, 'two fleshy muscular folds surrounding the opening of the mouth', though anatomically speaking, 'a structure or part encircling or bounding an orifice' is also acceptable." She shook her head to shift stray hairs away from her eyes and stared at him raptly. She'd always had a weak spot for his science rants.
Don't get distracted… She started at the sound of his voice.
"Will that suffice?"
"I'd like more specifics, if that's feasible."
"Very well," he leaned back, eyes shutting as his mind assembled further data. "In expanding from the anatomical, the lip is the labium, as on an insect, the flesh surrounding a wound, or the margins of the aperture of a gastropod shell. Further explanation is accessible in the ship's scientific archives on any of these definitions or their components, if supplementary information is necessary. Shall I continue?"
She leaned carefully against the wall, checking the ends of the hall for potential intruders before replying, "Please."
He hesitated, copying her cautionary glances, and fixed her with a curious stare that often prefaced a bluntly accusatory statement of suspicion. She swallowed. "A botanical lip refers to the protruding divisions of an irregular corolla or calyx, and a lip in music to embouchure." She relaxed, noting with relief that he was adjusting his position forward. "In returning to presumably your primary area of concern, the human lip is obviously divided into two structures: the upper lip, labia superfluous entafada and the lower, labium inferius. Both are comprised of tissue and covered in a thinner skin than that on most other parts of the body, specifically stratified squamous epithelium. The concave dip-" he scowled, hesitating and raising a hand uncertainly. "Between the lips and the-" she leaned her head towards her shoulder slightly as something once more arrested his explanation. The hand held aloft stretched into his habitual assured movements and a gentle finger came to rest above her mouth, between the two peaks of her lip. "This is the phitrum, and this," she kept her eyes trained on his calm and focused downcast gaze as he traced the outline of her lips, "is the vermi." His fingertip lingered at the beginning of its path until she smiled, shifting his attention to his animate model and jumpstarting his mental encyclopedic entry recitation. "The function of those structures," she compressed her lips to regain control of her smirk as he re-crossed his arms behind him, "are most notably those of food intake, sensory activity, facial expression, and articulation."
"Sensory activity?"
He blinked and quirked a single slanted eyebrow. "Indeed. The lips are a tactile organ and one of the bodies erogenous zones."
The time was approaching. "Expound."
He nodded. "An area sensitive to sensory stimulation. Three nerve groups have endings here." His hand rose again, confidently this time, and he placed two fingers beneath her eye, trailing them down her cheek. "The infraorbital nerves," he lifted the fingers and placed them on the side of her head, slightly above and in front of her ear, following an internal track across her jaw to her chin, "the trigeminal nerves," he removed his second finger, leaving the forefinger to sweep across her chin, "and the mental nerves." The contact was promptly curtailed this time and he concluded with a slight bow, "The environmental interactions with the organ thus produce sensory responses."
Realizing this was as much planning time as she could hope for, she made a bold move. "Could you demonstrate?"
He predictably rose an inquisitive eyebrow, "Excuse me, lieutenant, how would you propose such a course of action?"
"I…" she shrugged innocently, "from a scientific point of view, what would you suggest as the most time efficient and effective demonstration method?"
He inclined his head to the side, regarding her with the previously seen skepticism. "It seems you have a proposition you are attempting to force me to surmise. More precisely," she kept a surprised and mildly offended expression intact in face of his accusations, "based on your interest and final request I believe you are attempting to solicit a kiss."
"In the name of science, Spock," she intoned with as much solemnity as she could muster.
Both eyebrows. "Very well, Nyota. Focus on the nerves I mentioned," she smiled at this characteristic sarcasm as he raised her face to his.
Erogenous zone indeed.
"Bridge to sickbay, Kirk here,"
Uhura strode purposefully the few steps to the side of the captain's chair, communications details ready for a signature.
As the good doctor replied she whispered, "I've had the necessary funds transferred from your account."
Kirk muttered a reply while signing her apparatus and half listening to an inserted McCoy, "For what, what are you talking about?"
"The bet," she answered smoothly, taking the approved data.
"What!" Kirk turned to look at her for the first time in their discourse, immediately altering his volume after several officers cast an askance look his way. "When did you- I don't-" She grinned smugly. "Prove it to me," he scowled, stubbornly in denial that anyone had encouraged his first lieutenant to initiate a romantic interaction.
"You can ask him yourself, captain," she stepped up to the highest tier on the bridge floor, patting his head in mock sympathy. "You may be surprised to know that Vulcans share a similar facial nervous system with humans."