There already exist pickpocket-proof pants, with hidden interior pouches which only the wearer can reach. However, I would take it a step further and make ANTI-PICKPOCKET PANTS!
A battery pack and transformer generate a high-voltage current running through the fabric on either side of the pocket, but the circuit cannot be completed because of little plastic spacers. When someone reaches his or her filthy burgling fingers into the pocket, it completes the circuit and shocks the aforementioned filthy burgling fingers.
Of course, this means that YOU have to be wary and never stick your hands into the pockets without first turning off the electricity. Then you have to remember to turn it back on before entering a place with pickpockets. But hey, inadvertently shocking yourself is half the fun!
