How was queen Emeralda you ask? Boy what a woman, at her time all the captains were young, good-looking, boys; she had her fun.
Now don't get me wrong, she wasn't so bad for an aristocrat, she just had a hunger for fresh meat, if you know what i mean.
This elaborate dress was made using magical imbued cloths of various kind. Apparently is a very formal dress for woman, that cover almost all her body parts, someone could also call it prudish.
But the magical cloths of which the dress is made have the ability to be invisible only to the people selected by the wearer, this way she can attend formal event (like ball and so on ) looking very chaste to everyone.But when she met someone attractive, or a guy she want to tease a little, she can make some part of the dress invisible to him; showing an ample cleavage, a naked leg; being more “sexy” in various way and son on. If she wanted the whole dress could be invisible for the guy; letting him see what's beneath.
The effect vanish if the wearer take off the dress, there's virtually no limit to how many person the wearer can target, they just have to be in her line of view. After that the effect will continue untill the dress is taken off or the wearer decide to stop it.
A little bit of history
Queen Emeralda was a beautiful woman in her youth ( albeit considered ugly in her later years) who loved sex, good looking boys and showing off her beauty.
The problem was that her position required a certain discretion, so she came up with the “flirting” dress idea; and she liked it so much that soon all her wardrobe were composed of this kind of dresses.
At court was widely know that the fastest road to be a captain passed through her bed, and when at balls or mundane events a young man was faced with an half-naked queen, that a moment before was fully dressed, he knew what he had to do if he didn't want to jeopardize his career.
This wasn't much of problem in the younger day of the queen, tough it became a lot more awkward (for the selected guy at least) in her later years.
She lived a very long life and it's said that in her later years her approach was even bolder. She married and have gave birth many times (a thing that led to the demise of her beauty), her husband was a weak man completely dominated by her.
Even after her death the popularity of this kind of dresses keep growing, today they are even used for exclusive brothel's display by skilled dancer who play with the "you can see, now you can't" effect.
Known uses of the flirting dress:
This was inspired by a recent comic strip by oglaf (which i can’t link since it have some adult content) and the real character of Maria Luisa of Borbone – Parma, Queen of Spain
Cyberpunk / Sci-fi variant: (suggested by Longspeak)
This dress is made of an advanced fabric with the ability to change color, or even turn invisible, following the imput of the cortex implant of the wearer, even thought the producer didn't bother to create any other way of activation (after all who doesn't have a cortex implant these days?) a couple of this dresses were modded by some purist to respond to a remote.
The producer is a famous fashion firm that launched a line of "invisible fashion" called "The invisible line". The line include cloth for male and female, but the real innovation is the program that control the invisible/color changing fabric.
The basic version can "just" select (from a list of preset) which area of the dress have to be visible or have to change color, grating the wearer a lot of variation to use to show himself (even in cold area!).
The firm sell in his app store a costly upgraded version of the program that grant the wearer total controll of the fabric, playing with invisible area and color the dress can change every second, a moment being an intricate spider net the next an ever changing rainbow of colours. This app is mostly used as developer tool by artists and designers that create original designs and then sell them to rich and eccentric clients. This way the dress itself became the canvas of a whole new artistic movement.
Originally the fabric was developed by the military for the espionage sector (in which is still used as a sort of chameleon suit), in time it became surpassed by the latest invisibility tech; that grant total invisibility to user not only to his dress. After that the license was bought by the fashion firm.
Lately an hacker released on the net a new virus, called "fashion victim", that target the dress's program, take controll of it and use the dress to show the private message of the wearer and / or various porn images.
Additional Ideas (1)
You know that age old argument about chainmail bikinis? Maybe all those chainmail bikinis are really Flirting Chainmail??? All the protection of chainmail, all the fan service of a bikini!