They decide to wager their bikini bottoms

The two rivals were swimming in the cold ocean, hugging their arms for warmth. “W-what the matter? Can’t hand-dle a bit of s-sea water? Want to go your b-blankie to warm up?” Amanda taunted Evie.

“I c-can handle it b-better than you! I would bet my b-bottoms I c-can last longer than you h-h-here,” Evie replied without thinking.

“D-deal, whoever g-gets out of the water f-first loses her b-b-bottoms,” Amanda replied. Evie gritted her chattering teeth. She didn’t want to play this frigid game, but she wasn’t about to back off and give Amanda the satisfaction of winning… and of seeing her lovely derriere.

And so they kept swimming, legs kicking the water below, each trying to appear like they weren’t getting goosebumps on their whole body. They were utterly alone in the sea, as any sane person would not venture into the water. Their dormmates, meanwhile, were happily relaxing on the sand, building castles and playing volleyball.

“W-want to go p-play?” Evie asked. “G-go ahead, j-just give y-your b-bottoms beforehand.”

“Why d-don’t you go? B-bet you c-can ask the girls to b-bury you in the s-sand to hide your p-pale ass.”

“I'll show you p-pale, whooooaaaa!”

“Aaaaahh!” As if Neptune himself was tired of the bickering, a giant wave carried the two girls ashore and spat them out on the beach.

“You touched the sand first, so you lose!” Evie argued, lifting her head from the wet sand.

“No, you did!” Amanda eloquently retorted.