TheWife[sup]©[/sup] pretty much knows, but she really doesn't care. I don't get carried away and I NEVER lie about purchases. I don't tell her about every single thing I buy, nor does she tell me about every single thing she buys. We're not keeping secrets, it's just not a big deal as long as we don't overspend. I do the bookkeeping, so I know exactly how much goes where, but I have no idea about the specifics of her purchases.
I'm not sure what number that makes me...
Remember, there are 3 prices for every purchase you try to sneak in or lie about: the price you pay, the price you tell her you pay, and the price you pay when she finds out the price you paid. The last one is a big one...
I try to keep it in balance and just keep it at one price.