Disclaimer: Transformers is not mine, but I belong to myself.
"Um, why are you licking me?" Sideswipe asked, his bottom lip tickling slightly as Jessica affectionately slid her tongue on the softer metal used for face plating. The human just giggled and continued to lap at his lips, causing the red warrior to grin. Even though humans were small, they produced an exorbitant amount of different fluids, saliva at the top of the list. In just a few minutes Jessica had coated Sideswipe's entire mouth so it possessed a light sheen.
The girl bent forward and began working on his upper lip, pink tongue gently wetting his metal skin. Sideswipe grinned wider, trying to keep from laughing. The fact her boobs pushed against the underside of his bottom lip only worsened the feeling of having a small, soft pet on one's face. After a few more minutes the mech couldn't take any more and began giggling. On their own his lips pursed to keep his laughter in. Since Jessica's head hovered so close he didn't want to hurt her ears by laughing too loud.
"Does it tickle?" she finally asked.
"Yes, it tickles!" He chuckled one more time before adding, "This is the last time I let you room with me. What is it with you and licking?"
"I like licking," came the simple answer, and she licked his lips again with a happy wiggle of her butt to prove it.
"You're like a pet," he noted, "real affectionate, likes to be pet and stroked, and loves to lick. How would you feel if I licked you?"
"I dunno." Without warning Sideswipe whipped out his own tongue and gently dragged the tip from the base of her neck to the side of her forehead. Jessica widened her eyes and froze in surprise. Sideswipe's tongue was made of metal like the rest of him, but felt dry and extremely smooth; so smooth it didn't produce friction against her skin.
"Well?" Sideswipe asked, smirking smugly. To his amusement Jessica only grinned and laughed.
"That was cool!" In response, and thanks, she hugged his face and gave the middle of his upper lip a long and big ol' lick, touching it up with a light kiss.
"Would you two shut the fuck up? Primus!" griped Sunstreaker from the bottom bunk, kicking it under Sideswipe's skidplate. "I'm trying to recharge here, and you two are on the gross subject of human saliva and application of said fluid. It's disgusting; cut it out."
"But it feels good, Sunny, it tickles," Sideswipe countered half-heartedly.
"It's disgusting," the yellow twin repeated with a low growl. He kicked the bunk again, this time aiming for the small of his brother's back.
"Hey, watch it!" Sideswipe snapped. Sunstreaker only responded with a grunt, then rolled over to go back into recharge mode. Once all fell quiet in the room, the very faint sound of a wet tongue lapping resumed. "That tickles."