Offline/Explain how you were all just swimming and got your clothes wet

You reach for the only explanation that makes sense to you. "OH! We just went swimming and we got our clothes wet, so we took them off."

An eyebrow is raised. "You swam in your clothes?"

"Uh, yeah, we didn't want to go back to get changed, so we just kinda jumped in."

"But what you're wearing isn't wet." She points out. "You took off some of your clothes to go swimming?"

"Yeah, okay. So?"

Mom stares each of you down with her hands on her hips, a scowl forming. "What's going on?"

"Nothing! We were swimming!"

"We were just having fu-" Emma can't actually get a word in as your mom talks over her.

"But you're coming from the beach and what you're wearing isn't wet." Her brow furrows as she continues to put together the misshapen pieces you're supplying her. "You expect me to believe that the girls took off all their clothes including their underwear and then put their other clothes back on to go swimming which is why they're not wearing them now?"

You can feel your stomach rising in your throat. You want to say no, but you're already committed. "Yes!"

"Alright. Let's go to the beach."

"What? Why?"

"To pick up all the wet clothes you left behind."

"Mom! We... we got changed after!"

"Justice, you're coming from the river and you just said that you..." Mom stops herself and takes a deep breath. Unfortunately that doesn't calm her. "I'm not liking this! Why are you lying to me? Why are you really naked? Someone better tell me the truth!”

Emma shrinks into herself a little. "It's okay mom, really."

"It... it was a dare," mutters Asha. She's trying to come up with something more believable, but she's not helping things.

"A dare? What kind of dares are you doing exactly? Were you doing dares last night?"

"Mom! Geez! What are you talking about!? You're paranoid!" you exclaim, trying to push her away from any cabin-related questioning.

Asha backs away from her comment. "No, um... nevermind."

"We were only having fun," repeats Emma, trying to sound purely innocent but seemingly corroborating Asha.

"Nope, let's go! We're getting clothes on, right now!" Mom grabs Emma and Asha by their arms and yanks them past you. "It's bad enough that you're running around half-naked but you," mom emphasizes by poking your chest, "should not be encouraging this kind of behavior!"

"I'm not! Jesus! Why is our hair wet?!" you mention as proof of your lack of guilt.

"That's enough Justice! Don't talk to me like that! You should know better by now! And you do know you shouldn't be doing this because you're trying to cover something up!"

"Seriously! Mom! Just listen for once!"

"You listen, mister!"

"What's going on?" asks dad, wandering into this discussion. "There's an awful lot of yelling over here."

"Mom's going crazy!" you stomp, well flustered now.

"Can you take your son please? I'll handle these two."

"What's wrong?"

"Justice has the girls running around naked and he's lying about what they're up to."

Of course one glance at the threadbare girls and dad is completely on your mom's side. "Alright. C'mon Justice."

"But nothing happened!"

"That's enough. Let them go. We'll talk about it after breakfast." Dad guides you toward camp while mom marches the girls back toward the cabin.

Fuck.

- - -

You get quite the lecture over the course of the day. After Mom finds the heap of clothes left outside your cabin, and the scattered contents inside, she digs deeper and deeper into what you've all been up to. Asha is the only one to admit to little tidbits here and there but nothing particularly damning overall. It's clear that mom suspects something more perverse was going on but she can't immediately get enough details to really put anything together. It's not until she starts cleaning up the cabin and notices the smell of pee at the top of your sleeping bag. Pee in a sleeping bag wouldn't itself be anything especially incriminating but the fact that it's sprinkled around your pillow with the outline of a head in the center is pretty bad. That bit of evidence, even without an admission, is enough to make them certain that you're lying, if only by omission. But your sketchbook containing recent illustrations of young naked girls really screws you over.

Mom moves out into your cabin with Emma. You're forced to bunk with dad. Since you're unwilling to tell them what really happened they assume the worst and you're kept well away from both your cousin and your sister and effectively held under cabin-arrest for all of the next day, only being let out for meals. They end up deeming that either too cruel or too bothersome and let you out for that night's campfire, but tell you quite explicitly to leave Emma and Asha alone.

The rest of the vacation is horrible. You don't know what or how much mom told everyone, but it's enough to get some scornful looks and selective isolation from your extended family. You catch your sister looking at you from across camp more than once, but you can't tell whether her expression reads as depressed or betrayed.

Whelp, you started this trip lacking any substantive relationship with your sister, and it looks like you'll end it that way too.