Later in the afternoon Katlin and Gavin took a walk along the shore.

“I love how white and soft the sand is here,” Katlin said.

“Yeah,” Gavin agreed. “Hardly any shells.”

“I like shells,” Katlin said. “Especially the kind where you can put them to your ear and hear the sea.”

“Those are conches,” Gavin told her. “And the sea is right here. You can hear it without a conch.”

“I want a conch,” Katlin pouted.

“I’ll keep my eyes open,” Gavin said.

A few dozen yards down the beach, he spotted something. “How about this?” he said, holding up the shell he’d found.

“That’s not a conch,” Katlin said.

A sad expression crossed Gavin’s face.

“But it is a very pretty blue,” Katlin allowed. “And also it looks a little like the head of your penis.” She laughed.

“Really?” Gavin questioned.

“Really and truly,” Katlin said. “It’s even about the same size. If you don’t believe me, tug down your shorts and we can compare.”

Gavin looked around.

“Don’t worry. Nobody but me near enough to see,” Katlin said.

“What about those guys we passed playing volleyball?”

“Why would they want to look at your cock?” Katlin asked.

“Maybe they’re all gay,” Gavin said.

“Then good for them,” Katlin said.

“That reminds me,” Gavin said. “You know what day it is today?”

Katlin thought for a moment. “January 8?”

“No. I mean right, but what day of the week?”

“Monday.”

“Right. Monday. Masturbation Monday. And this week it’s your turn.”

“Here?” asked Katlin.

Smiling gravely, Gavin nodded.

“What about those volleyball guys?”

“You said they were gay. Come on, do it. The sand is nice and soft. And no shells, except for the blue penis shell.”

Katlin lay upon the soft white sand.

“And take off your top so I can see your tits,” Gavin said.

“Why do you want to see my tits?” Katlin asked.

“Because they’re beautiful. And I love what happens to your nipples when you’re aroused.”

“You’re so naughty,” Katlin said, but she took off her top and handed it to Gavin.

“Okay, now touch yourself,” Gavin said.

Tentatively Katlin moved her hand down her tummy. Her fingers eased beneath the waist of her bikini bottoms. “I can’t,” she said.

“Why not?”

“I’ll stretch my suit.”

“Take it off.”

“Really?”

“Really and truly. I need to see your puss when you touch yourself. It’s so beautiful. So special. So hot.”

Katlin eased her bottoms over her hips and off. She handed to Gavin. “The volleyball guys aren’t looking, are they?” she asked.

“Don’t worry,” Gavin said. “They don’t have binoculars.”

“Very funny,” Katlin said.

“Touch yourself,” Gavin commanded. “I need to see you come.”

Katlin touched herself. Her fingers circled her clit. Dipped into her cunt. Circled her clit again.

“So pretty,” said Gavin after a while. “I can see the juice starting to come.”

Katlin moaned. Her fingers moved faster.

“That’s right,” Gavin said. “Oh sweetie! The juice is almost to your little asshole. Come now. Wait. Take off your glasses so I can see your eyes when you come.”

Perhaps Katlin didn’t hear. Perhaps it was too late. It didn’t matter. Her eyes were squeezed tight shut when with a shuddering gasp she came. Gavin had to content himself watching the orgasmic contractions of her cunt and the pulse of her asshole as it swallowed the plentiful seep of Katlin’s girl cum.

Afterwards, Gavin helped her balance as she stepped into her bikini bottoms and refastened her top. Hand in hand they strolled back the way they came, past the grinning volleyball boys and up onto the boardwalk and into their beach rental where Gavin helped Katlin off with her suit.

“Oh no!” Katlin said.

“What’s wrong?”

“We forgot my special blue penis shell. Would you run back and get it for me?”

“I have something better for you,” said Gavin, pulling down his shorts.