If you’ve been properly pickpocketed, you won’t realize you’ve lost your wallet until you need it next — most likely long after the crime has occurred. You’re more vulnerable to pickpockets when you travel, because many thieves make a living by stealing from wandering tourists who carry more cash than others.
A Frommers post from last year says where you hold your wallet will determine how likely it is that a pickpocket will be able to make off with your money.
Places you shouldn’t keep your wallet include a backpack, purse or your back pocket. When your wallet isn’t near your hands or in your line of direct sight, thieves can distract you and make a clean break.
Frommers recommends keeping your cash in a pouch under your clothes. If you don’t feel like going that dorky, the front pocket of your pants also works, and the inside pocket of a jacket isn’t so bad either.
How to Avoid Being Pickpocketed [Frommers]