Resisting the urge to return to the pool you grab a towel and dry yourself off. Wrapping the towel around your waist so you don't drip on the carpet you head into your room. When you get there and remove the towel you could swear your swim trunks go farther down your legs than they normal would. They're also clinging tightly to you now. Apparently keeping the towel on just pushed the change along a little further. A quick check reveals your swim trunks are definitely not coming off.
You grab a fresh towel and make sure you're as dried off as possible. Then you go for your phone and dial Lydia. It rings and rings with no answer then you finally get Lydia's voicemail.
"Please call me - something strange is happening."
You lay in bed for several minutes, but there's no answer. Then you hear the front door open. You go to see who it is, but stop as you're about to leave your room. You realize that despite your swim trunks you're basically naked now and you grab some pants which you hurriedly put on.
Heading downstairs you hope it's Lydia, but it's just your parents home from work.
---
You make normal small talk with your parents over dinner. The topic of senior prom comes up; the big event is that weekend and your parents wonder about your post-prom plans. You don't know your plans yet, but guess there will be a party somewhere. Your parents just want to make sure you'll be safe and act responsibily, which you promise to do.
After dinner, you head back to your room and check your phone, but there's still no call from Lydia. Another call also gets her voicemail.
You eventually go to bed without hearing from her and hope nothing is wrong.
---
You wake up in the morning desperate for a shower before school so you try to take the fastest shower possible and dry quickly. Even so, the latex-skin that was your swimsuit has now crept down almost to your knees. Strangely, your manhood is not clearly visible despite the snugness and you fear the worst. But the need to relieve yourself becomes strong and a familiar sight emerges from a slit in your groin. Your business done, it slides back in leaving nothing exposed. You now have psuedo-indoor plumbing, which you figure makes sense if you're turning into a merman.
Lydia still doesn't answer her phone in the morning. You're relieved to find her before school starts and pull her aside where you think nobody is in earshot.
"No good morning kiss?" she asks a little dejectedly.
You give her a quick kiss, but your mind isn't on romance at the moment. "Something's happening."
"You heard about Monica's post-prom party at her parent's beach house?"
"...no. But bigger than that."
"Someone else is having a party?"
"I'm changing."
"Into what?" Lydia asks with a surprisingly lack of surprise.
"A merman, I think. It seems to be the same sort of way you change: I went for a swim last night and when I got out of the water I couldn't remove my swim trunks." After a moment you add "I'm really sorry now for putting you through what I did. I meant it earlier when I apologized, but going through it myself now I can really understand what it's like. I'm pretty sure I'm going to end up a merman, but it's scary not knowing what's going on."
Lydia didn't say anything for a moment. Finally she spoke: "What it's like to be like this..."
"What?"
"We've both been carless with our wishes."
"What do you mean? You rubbed the lamp but the genie didn't come out."
"It did later, when I went downstairs to get my pants."
"You hadn't mentioned that. Did the genie give you any answers?"
"Not really. He couldn't or wouldn't do anything about my situation and I was so frustrated at that moment that I was thinking out loud and..."
"And you made a wish?"
"I wasn't even trying to! I just accidently used the word 'wish' out loud and the genie took it as a wish."
"What did you say?"
"I wish my boyfriend would know what it's like to be like this."
"Yikes. That is pretty open-ended."
"Open-ended. That's how he described your wish too."
"Geez. I should've known better than to mess with a genie. At least I'm turning into a merman instead of, I dunno, a woman or mermaid or whatever else the genie might've interpreted your words to mean."
"I only like guys so I guess he interpretated my thoughts and feelings too."
"You fantasize about mermen?"
"Since you turned me into a mermaid, yes, the thought of you with a tail has crossed my mind once or twice..."
The school bell rang.
"Are you going to make it through a day of school with your transformation started?" Lydia asked. "Or do you feel a little ill and need me to take you home?" she added with a mischievious look.