Go swimming

Vanessa approached Lauren, who looked up with a comical grimace of fear on her face.

"Well, time to get off your butt!" Vanessa said, pulling Lauren up by an arm. "We didn't come to the beach just to sit around!"

Lauren struggled to her feet, all the while trying to keep her bathing suit in place. Her peers watched in amusement as she flashed half her ass unwittingly before she got her bottoms back in the right order.

"What do you want me to do?" Lauren asked meekly.

"Go jump in the water!" Vanessa suggested. Lauren balked.

"But... but my suit is barely staying on out here!" She pointed out.

"Well, if you want to keep MY suit, that I bought and lent to you, you'll do as you're told!" Vanessa whispered. Lauren's eyes bulged wide. She knew her wicked sister meant it. Lauren turned, starting towards the water. Vanessa ushered her off with a slap to the butt, causing Lauren to blush bright red while everyone laughed...