Use The Bikini Bottoms.

"We can use your bottoms. You can just wear your shorts." Jessica said.

"Well, I guess I have ****." Sarah sighed.

"I suppose we could use your bikini top instead, but you'll have to take your shirt off first."

"No. Just hurry up."

Jessica wiped her sister's pussy clean with the bikini bottoms. "Ew, now they're all dirty." she said, dropping them in the sand.

"Hey! Pick those up."

"I'm not carrying those piss stained bottoms, and I'm not putting them in the bag, they'll soak everything."

"Fine, just get my shorts on so we can leave. I'm still bottomless if you haven't noticed."

Jessica glanced over to the bush which was oddly still now. Was it the wind after all?, she thought. She pulled the shorts up, finally covering her sister up again.

They made their way back to the car. Walking by the empty parking lot and onto the streets. Their car was in sight and so were a group of boys. Familiar faces. It was the three boys they'd sat next to at the beach. What a coincidence that they parked right next to us, Jessica thought.

Meanwhile, Sarah could feel something quite troubling. Her shorts were beginning to slip down. She thought it might've just been in her head. A few more steps and she definitely felt them slipping that time. She wasn't sure how far they'd be able to fall before they said hello to the ground and she didn't want to find out. "Pull my shorts up." She said.

Jessica looked down at them. "They look fine to me, just wait until we get in the car."

"Hmph." Sarah replied. Looking down at her crotch worryingly. She spotted her bush peeking out at her. Her face went red. Oh my god, I never thought about my bush. I can't even shave it by myself. I hope nobody saw that on the beach, she thought. She could swear her shorts were slipping further and further although it didn't really look like it. If she had her bikini bottoms on she wouldn't have minded so much but now she was going commando. They were getting close to the car now and her shorts felt like they were definitely about to fall off. Eventually Sarah got too scared when she felt the shorts slipping and stopped. She spread her legs to prevent them from falling any further "Jess, seriously. They're gonna fall down. Help me." She said.

"The car is right there. Come on. They're not going to fall. Stop being paranoid."

Jessica noticed that the boys were sitting in the car, not moving. Chris was in the driver's seat and she watched as his eyes bugged out as Sarah waddled by the windows. Jessica opened one of the doors in the back of their car and tossed her bag in. Sarah was carefully waddling along around the back of the car. She went out onto the road to the passenger side door and waited for her sister to open the door for her. Jessica closed the door and looked back to the boy's car. They don't seem to be in a hurry, perhaps they're waiting for something to happen. Well, I guess I'll give them one last thing to look at. They were very kind for watching our things after all. She giggled. She walked around to her sister, smiling at Chris and the other boys as she did so. He waved back and Jessica opened the passenger side door. Sarah was standing behind it and had to walk around to get inside. Jessica wasn't going to let that happen yet. She reached down and with surprisingly little effort the shorts fell down onto the road. This was even more amusing for her because the boys could see the shorts around her ankles but the door was blocking their view.

"Jess!" Sarah yelped. "Pull my shorts back up."

"Come on, Sarah. They just want a little peek." Jessica laughed.

"This isn't funny."

Chris started up the engine and their car began moving. It seems like the boys are done with the beach for today.

"Quickly, Jess, they're going to pass us, they'll see me!" Sarah begged.

"Oh, calm down, I was only teasing." Jess started pulling up the shorts and it seemed like Sarah's butt was going to be spared from any unwanted exposure. "Ugh, your butt is too big."

"What?!" Sarah asked, scandalized.

"It's too big, I can't pull them up."

"Stop fooling around, Jess, these shorts are too big for me if anything."

"Nope. I can't seem to get them up." And just as she said that the boys drove past and got their final view of Sarah's perky cheeks jiggling as Jessica pretended to struggle with the shorts. After the boys drove away, whatever was preventing the shorts from being pulled up seemed to disappear as she was finally able to pull them up.

"Oh my god. Jess, they all saw my butt because of you. Why are you like this?"

"You should be glad they bothered to look at all. You won't have such a nice looking butt forever, you know." Jess reminded her. "Anyway, I guess we should really go back home now. Mom will be getting worried that we're out so late."