If you want the bad guy to know you are armed, get a CCW t-shirt and bumper sticker. You can order them off Zazzle | Custom T-Shirts, Personalized Gifts, Posters, Art, and more
. Find a design you like and you can have it put on anything, even a coffee mug or refrigerator magnet.
If you don't find any design you like, tell me what you want it to say or look like and I'll design it on zazzle and you can order it. I did a business logo t-shirt for KWGaryM and it's nice, they do a good job.
And the bad guy can be prepared for me and my gun, but I bet he doesn't know I have another gun he's not even suspecting in addition to the first gun. Either that or I'll just kick his ass for him and save my ammo.