Interactive outfit elements that let unfamiliar people around you know if you're up for a conversation. It can be a straightforward message ("I'm willing to talk", "You can talk to me", etc.) appearing on your T-shirt whenever you activate it or it can be something more subtle like a color change of a bracelet or other accessory to indicate your mood.
The novelty of the idea is to make indicative features appear and disappear upon user's will.
Reduce social anxiety for both sides when it comes to socializing with strangers or people you don't know well.
Making this interactive (the appearance of the message or other symbolic indicator is controlled by the user) gives more flexibility and convenience to the user since they can activate and remove the indicator whenever they want without changing the outfit element (e.g. taking the T-shirt off).
This could be useful not only for communication with strangers but sometimes with familiar people as well.
If a variety of such interactive products were available, people could choose a way to indicate their willingness to communicate, from the most straightforward (big lettered message on your T-Shirt), to more subtle ones (a change of color of your bracelet, a symbol appearing on your jacket, etc.).
I see this branching into two main options:
A direct indicator - written message appearing on your clothes/accessories.
Have an interactive pad attached to the front of a T-shirt, a jumper, or a jacket - just a thicker layer above the fabric containing a microchip and other materials serving as a simple screen.
A Bluetooth-enabled microchip receives signals from your smartphone. You control the screen through a dedicated app, you can choose when to display and when to hide the message (the screen then takes the color of the rest of the fabric and is hardly noticeable). If the system was more sophisticated, you could choose different messages to display.
A subtle indicator - change of color of an accessory, a symbol appearing/disappearing on it, etc.
The same technological approach would be used as with direct indicator. Bluetooth connects your phone or a smartwatch with a dedicated accessory, you then control the process through the app. Alternatively or additionally, physiological sensors implemented into your smartwatch could monitor your mood and the system would change the indicative colors/symbols automatically. This would be like an improved version of a mood ring. The same automatic approach is also applicable to the direct indicator option.
A pro of a subtle indicator approach is that you can indicate your mood/willingness to communicate subtly (suitable for more modest or shy people) and it is like a game of waiting for those who will notice it and act upon it.
A con is that people around would have to know that a certain outfit element is dedicated to signal about your mood/willingness to talk. So it would have to be of a certain, uniquely indicative design, similarly to how you can't confuse crocs footwear with anything else. If all crocs slippers were made interactive to signal the wearer's surroundings about their willingness to communicate through a color change, someone seeing a person wearing crocks of a certain color would know for sure that this is an indicator about their willingness or unwillingness to talk.
A universally accepted coding system should be used, meaning that people familiar with such smart accessories and recognizing them should also know which color/symbol represents which mental/emotional state of the wearer.