Spike, Although...

The library, as it turned out, had maybe ten ponies there that day, most of them noses buried in books or copies of the local paper. The librarian noticed them as they entered, and waved a friendly hello, but beyond that, they were free to slip into the rows of books with Spike's half-hard cock still begging for attention and Rarity sneaking her hoof into the tail-hole of his skirt the moment they were out of plain sight.

"Rarity," Spike whispered. He felt Rarity's hoof moving along his tail, making him shiver, and going even further, past the base of his tail, pressing into his butt and giving his cheeks a squeeze... the rest of his sentence fell apart into a desperate murmur, which he only just managed to block by covering his mouth with a claw before the moan escaped. Rarity smiled at him with a single eyebrow raised.

"Hmm?" she said, pretending obliviousness. "I'm sorry, Spikey, I couldn't hear the rest. Do you mind repeating what it was you said?"

"I was saying," Spike began, once again noticing Rarity's hoof begin to trace and explore underneath his skirt, "that we have to be really quiet or we're gonna get cau... cau..."

Rarity had snuck another hand underneath Spike's skirt the traditional way, and was massaging his butt from one cheek to the other, smirking as Spike rocked his ass back into her gentle squeezes, and bucking his hips forward in the other direction to press his cock up against the skirt and the skirt up against one of the rows of books separating them from the open view of the common room and the watchful librarian.

"What's that dear? Speak up, you're still a bit faint." Rarity's eyes sparkled mischieviously as she continued her booty-squeezes.

"We have to be quiet," Spike managed between muffled grunts, his cock twitching each time he rubbed it against the book-case. "Or... unh... we're gonna get... unh... caught..."

"Oh, heavens!" Rarity feigned a gasp of shock, with a hoof to the side of her face. "We wouldn't want anything like that, would we? Somepony catching me playing with your adorable little behind, in a public place like this, hmm?"

"N-n-nooo," Spike managed, his body wracking back and forth between Rarity's exploring hooves and the friction of the book-case. He could barely keep his eyes open, and each time he thrust his hips forward, he let out a tiny little grunt into his arm, his claw clutching onto the book-case for support.

"So I suppose I'd better not do something like this, should I?"

Rarity had reached forward with one of her hooves and taken hold of Spike's aching, rock-hard, prepubescent, precum-leaking cock, and the moment he felt her hoof alongside his shaft, the poor dragon came, shooting a hot, stick stream of his jizz into the underside of his skirt and spattering it all over his legs and feet.

Spike leaned forward and bit his arm hard to keep from screaming. His hips kept rocking, and with each spurt of jizz that shot from his cock, he let out a muffled moan, his eyes clenched shut, his body moving through his orgasm on autopilot and leaving the watchfulness to Rarity.

"That's it, baby... let it out, let out all that cum for Mommy," Rarity cooed, stroking Spike's shaft nonstop and licking her lips lustfully as she watched the hot, potent load spill from the head of his cock and down to the ground like a viscous, virile waterfall.

Spike grunted and grunted and moaned and moaned and came and came, until eventually Rarity removed her hoof from his cock and butt, and let the final dribbles of white gold drip from the head of his cock and land with a quiet 'pap' on the library floor.

Even though nopony had come by or seen them, Rarity and Spike could hear murmurs from the other side of the book-case.

"Good job, my dear," Rarity said. She gave Spike a pat on the head, then a kiss, on his lips, which lingered just for a moment before pulling away, and left Spike hanging in mid-air, his eyes closed, his lips pursed with a dreamy expression on his face.

"Let's take our leave before we're asked to do clean-up duty, hmm?"

Spike nodded, and took Rarity's hoof with his claw as she led him down the row of books and around towards the exit, all with the knowing expression of somepony who has just coaxed a hot load of someone's balls in a library without being caught. You know, that one expression. I'm sure you know exactly what it looks like.