Before you can even get halfway to the changing rooms, you find your way blocked by a shop assistant who might have appeared out of thin air for all you could tell while you were rubbing your eager hands on the silvery fabric of the tail.
The girl is no more than five feet tall, but petite and very nicely put together. She is wearing a short skirt, black tights, skateshoes and a tight tshirt that leaves her midriff exposed to reveal a toned body beneath. She has long auburn hair tied back and large green eyes that are looking between the costume and your ever reddening face with an expression of amusement and something that might be playfulness?
"Can I help you with that?" she asks.
You manage to mumble something about the costume party and one size fitting all whilst glancing at the changing rooms over her head.
"You must want that for a female friend," she nods at the tail and adds a conspiratorial wink, "let's see what we can do about getting that sized for you." She takes hold of your hand as she turns towards the changing rooms.
"Would Sir care for a demonstration?", she asks as you reach the booth. "We can't have you spending your hard-earned cash on something that doesn't live up to your expectations when you get it home, can we?"
Are you loosing it, or is she comming on to you?
Seems that she is as she bundles you into the booth and pulls the door shut behind her.
You sit down on the stool in the corner and watch as she takes the tail from you and hangs it from the back of the door. Next she pulls her tshirt off over her head and lets her hair down revealing her breasts cupped in a black bra. They're not huge, but they're far from tiny and have a fine shape to them all the same.
The shop assistant slips off her shoes and then turns her back to you to pull off her panties and roll down the black tights. You watch her reflection in the full length mirror as she finally slips off the skirt and bra last of all.
The assistant tosses aside the blonde wig that she finds clipped to the tail and instead ties the seashell bikini around her breasts and steps into the tail.
She slowly rolls the tight-fitting costume up over her legs like an over-sized stocking, making sure to bend over and wriggle into it as much as she can.
You're surpised by how closely the silvery tail hugs her body and pulls her legs together as she eases it ever further up towards her waist. It seem at once to both cling to her legs and somehow hide the fact that they're separate limbs rather than a single tail.
Rather than stretch like lycra, the fabric of the tail seems to stretch to fit her body a little at a time so that once a stretch of her legs have been covered, the material refuses to move as the next is covered in turn and instead clings snugly to her like a second skin.
Soon she tugs the tail up to her waist and smooths it around her buttocks, despite the fact that you can't see a single crease anywhere along its length. The assistant regards herself proudly in the mirror and glances back over her shoulder.
"See Sir," she giggles, "one size fits all."
With that she sits down on your lap and makes sure that you feel the silky and smooth quality of the tail by massaging your lap with her buttocks.
She lifts the tail up and you notice that the tailfin has begun to flap as she moves. You wonder if that would be a sign that a mermaid is getting somewhat aroused.
As the movements of her tail become more sinuous and fluid, you notice a change in the eyes of the amerous shop assistant you have just watched transform herself into a silver-tailed mermaid.
"That costume seems to have brought out your wild side," you comment.
"What costume?" she replies in a rather puzzled voice...