You're floating on the surface when something splashes you, startling you. You look around but nobody and nothing seem close by.
Water splashes the back of your head. You spin around quickly but find only ripples. Someone or something seems to be toying with you.
Then you see a tailfluke lift out of the water and splash you again. It seems a dolphin is playing with you. You like dolphins and think it would be neat to swim with one, but then you remember you're naked and you've heard how frisky dolphins can be.
You feel the dolphin's tail brush your leg and deciede you had best swim back to shore.
Before you get far, you hear a voice behind you ask "Leaving already?"
You stop; that sounded like your girlfriend's voice. "Katie?" you ask. In the moonlight, you can see a head sticking out of the water.
"Hey Bobby" she respondes meekly. "Nice night for a swim?"
"Uh...yeah. Where have you been? I couldn't get ahold of you or find you anywhere."
"I guess you could say I went for a swim too."
"For the last 24 hours?"
"I spent some time on the beach, but yeah I've been in the ocean pretty much all day."
"How is that possible?"
"It's the full moon."
"You're a werewolf and you've been doing the dog paddle all day?"
"Not exactly..."
"No more riddles, Katie! Where do you disappear to every month? What's going on? You worry me sick."
"I'd say you wouldn't believe me if I told you, but since it's the full moon right now I have proof."
With that, Katie slowly dives backward. You get a nice view of her breasts and her flat stomach and...her tail?! There's no mistaking that below her stomach is a dolphin's tail. The flukes give you a little wave before disappearing under the water. A moment later, Katie breaks the surface close to you.
"So what do you think now that you know I'm a were-mermaid?"