From time to time, someone in the global AB/DL community decides to promote some kind of wearable symbol of alliance and kinship. So with this thread I throw my hat into the ring as well. :-)
Why, do you ask, would one want to wear neon shorts with flashing LEDs across the butt that spell out "I AM AN ADULT BABY / DIAPER LOVER"? Well, for most people the idea is for like-minded individuals to find each other, and not to advertise our status/desires to the general public, so none of the ideas are that obvious. There have been a couple of vague but creative and memorable designs released in the past. The most well-accepted symbols I've seen are this pin from 2002 and this flag created in 2005. I think there are four reasons these symbols have not been as widely used as their creators had hoped: first, someone has to pay for supplies to make them; second, someone has to have the ability to make them (or can pay to have them made elsewhere and mailed); third, someone has to wear them; and finally, unless you have many pieces of flair (and some of you do and that's awesome!), it will stand out and attract way too much interest. If someone sees a unique and colorful symbol on your outfit, they'll be intrigued and ask you about it. That's perfectly fine in those situations where people are expected to "let their freak flag fly", but if you're not in that position, you'd have to have a good cover story ready. They might go find the real meaning through Google anyway, and there goes your secret...
So here's the first part of my idea: On all my T-shirts, I have attached a safety pin to the bottom hem that hangs at the front of my right leg. I call it my shirt-pin. Sometimes people will ask me why I am wearing a safety pin on my shirt. Well, because it's useful - at different times I've used my shirt-pin to replace missing buttons, to push reset switches on gadgets, to clean under my fingernails, to stand in for a paper clip if I can't find one, etc... I can tell which batch of laundry is mine by finding my shirt-pins. I could even pick a handcuff lock, maybe, if I had to... The utility is undeniable. Nobody's ever given me grief for having a shirt-pin. They might even think about wearing one too!
Which leads to the second part of the idea: If you see someone wearing a shirt-pin, simply ask them: "May I ask why you have a safety pin on your shirt, or are you trying to keep it on the DL?" (I mean DL in the slang sense "down-low", or as Wikipedia defines it "Keeping an act, action or some other piece of information a secret".) A random individual will respond with the myriad reasons they've found their safety pin useful. But anybody who is in on the secret will understand they were just asked about their shirt-pin by a fellow AB/DL! If that happens to me, I plan to say "I appreciate the pun!" and then introduce myself from there.
So there you have it - if you want to participate, simply find some safety pins, apply one to the bottom hem of your shirt, and be on the lookout for others with shirt-pins too. Happy hunting!
TL;DR: In which I propose applying a standard safety pin to the bottom right hem of your shirt, and looking out for others who are doing the same!