I usually put my wallet in the front jeans pocket that is way too tight for anyone to pull anything out (heck, even I have problems sometimes), let alone unnoticed. This of course wouldn't protect me from outright robbery or someone snatching my wallet while I have it in my hand, but I think I'm pretty safe from simple pick-pocketing.
"Imagine" by HCE | Hitler reacts to Battle of Montreal | An alternative use for squid that has never crossed your mind before