Here's how I do it:
I buy identical black nylon zippered gun cases and slip them under the bed, with a few in the back of the closets. Still more are in strategic corners. The key to this plan is to move them around frequently so the wife never knows how many you actually have. Oh, when I get one at the gun show I make sure I buy a case for it then and there and I don't take it into the house until on the way IN from an announced range visit. Seems my wife doesnt count how many I take to or come back with from the range.

Now all I have to do is figure a way to disguise the UPS man when he brings my cruffler purchases. :)