In a right-handed world, why is a man’s billfold pocket on the left side?
http://www.straightdope.com/classics/a1_395.html
[Pockets have always tended to be placed on the left side, for reasons that have little to do with the free expression of minority rights. The Roman toga is said to have had just one pocket, which was invariably on the left, and in fact the Latin word and latter-day heraldic term sinister, “on the left side,” is supposed to have derived from siniis, “pocket side.” No one knows who exactly decided to put the wallet pocket on the left (wallet pockets and hip pockets in general came into fashion in the 1890s), but the reason for doing so is obvious: you may extract your wallet from your pocket with your left hand, but you fish the money out and hand it to your creditors with your right. By such means as these are left-handed persons coopted into cooperating with a right-handed world.]
Being a rightie/wanna be ambi, my understanding of Self-Defense 101 whether in Eastern or Western Tradition, says to always keep your best hand free to get/use weapon, Sword or Six-Shooter. Protect your valuables with your Left/Other Hand and Protect your life with your Right/Best Hand. That’s why the simple act of shaking hands is such an act of trust in that it gives your opposition time to take a possible advantage. It also allows you to keep your left hand on your pocket/purse in crowds and your right ready for action.
If this was Family Feud, I would say, "And the #1 Answer to the Question "In a right-handed world, why is a man’s billfold pocket on the left side? is… but I wouldn’t let Richard Dawson kiss me.