This is a second wallet that has a small amount of cash in it that I can fork over to a robber should, heaven forbid, I ever am faced with the situation.
I started this practice when I began working night-shift in a city. (I'd lived and worked only in small towns before that.)
The practice is pretty simple: All you do is buy a new wallet, then put your old one in your other back pocket. Put a few small bills in it, then save the fake credit cards they send you in Visa or MasterCard offers and stick them in there to make it look more realistic. (You'll have to change these out every so often as they are generally cardboard and will start to wear out. And make sure they say "Your Name Here" and don't actually have your name or personal info on them.)
One of the things I'm mocked on is that, in my fear of the robber, I'll forget and give him my real wallet. That's possible, but those of you without robber wallets have a 100 percent chance of giving up everything in your billfold. I at least have a chance of not doing it.
The only bad part of carrying a robber wallet is that once you start you can't ever stop. If you say to yourself, "This is a safe place," and leave it at home that might be the very moment you get robbed, and you'll kick yourself for the rest of your life.
Not being a woman, I can't advise on this for the opposite sex. I suppose thieves want to grab the whole purse and not just a wallet. Maybe a purse-carrier can advise me on this.