For anyone who carries their wallet in their back pockets (I am just as guilty), STOP!
Placing your wallet in your back pocket WILL throw your pelvis out of whack, whether you are sitting directly on it or it is off to the side.
The thicker the wallet the worse it is. It is not uncommon to have someone relieve a good percentage of their back and hip pain simply by removing the wallet and placing it in a jacket pocket or front pant pocket.
Food for thought!