Logistical problems: Unintended Consequences!

After a fun day of swimming in the lake with your sister and cousins, and watching Adrianna sun bathe, the first evening rolled in. An evening barbecue was enjoyed, and then a logistical problem turned up that you had not even thought of! With the shrinking of the cottage, and the number of people here, there was only so much water for showers.

"I think we've got enough water for twenty minutes." Uncle Joey reasoned. "So if we had four partners, we could each get five minutes, but there is also Rose."

"I don't mind sharing." She said, meaning with your parents.

"That settles it then!" Joey jumped up. "Adrianna and I are going to go first!"

The shower was running for maybe thirty seconds before everyone could hearing moaning coming through the walls. Another logistical issue you hadn't thought of! Sound travels! Judging by the smirks from around the table, everyone was more amused than peeved.

"To think that a gorgeous woman like that would fall for my brother!" Your mother mused. "What does she even see in him?"

"If you remember what we saw in our adolescence," Rose joked. "He has got quite the parts down there!" Perhaps two glasses of wine with dinner had been a little much, but everyone was laughing.

The three other adults took their turn next. Everyone as quietly sitting around the table, trying to hear what was going down. It was strange that thinking about your parents with your aunt was turning you on like this, but all you could hear was the occasional giggle.

"I guess we're next." Robin said cautiously.

You followed your sister, trying to hide the upright shaft in your waistband, fully aware that she would see it soon enough. Reaching the shower door, you realized why the three had been laughing. The shower was tiny. With you and your sister inside, your bodies would be pressed right up against each other. It was amazing that three people had fit here.

Your sister quickly took off her shorts and then her bikini bottoms, and then jumped into the shower, eager to get rinsed off.

"Oh come on!" She said. "It's not like I've never seen your boner before! I just want to get rid of all the sand stuck to me!"

As you pushed down your shorts, your penis swung upwards and your sister's eyes opened wide in surprise.

"It still shocks me though," Robin said. "How big it is... Now hurry!"

You pushed into the shower, fully pressed up against her back. Penis pressed firmly against her bum.

The water began pouring down, warming them up. Robin picked up the soap and began washing herself. Reaching forward around her body, you helped wash any bits of sand off of her stomach and then her breasts, before making sure there was no sand around her pussy.

"You going to do anything about that thing?" She asked a couple minutes into the shower. "It's making it hard to move and wash."

"Well..." You stumbled. "I normally, you know... jerk off in the shower. It must be jumping up for routine."

"Well, uh. Maybe take care of it then!" She said, focusing on shampooing her hair.

"You're serious?" You asked in disbelief. Your sister was asking you to masturbate directly behind her!

"Yeah." She said, unable to turn to face you. "I've seen that you've been hard almost all day. Especially from watching Adrianna... You need to get it out, and I don't want you making a mess in bed!"

"Okay." The words barely left your mouth before your hand was wrapped around your member and stroking.

The feeling of her butt, and the situation were really helping you get off, when a knock came at the door, and the door swiftly fell open.

"You didn't lock it!" Robin gasped.

"That's five minutes!" Joey shouted, watching you two stunned.

Even in the steam, he could clearly see your hand wrapped around your shaft, and the lack of space between your bodies.

"Sorry!" He said, closing the door slowly, peering in at Robin the whole time.

"I'm sorry too." She said turning off the shower. "Maybe next time you'll be able to relieve yourself."