My wife caught me surfing a few guns sites...Travis' suggestion actually. She knows what that means...I'm poised for a purchase. I caught an earfull especially after I questioned her how one could possibly spend $150 on a haircut and color last week. Seriously...$150? That could have purchased a used 10/22 or at least a new scope that would last a lifetime!
Rookie mistake times two.
First never let your wife catch you researching a well needed and well deserved purchase.
Secondly, you critized her haircut cost? Have you gone mental?
When she comes back from her hair appointment tell her how great she looks and that she looks better than the day you married her. Then say something like "you know honey, I'm concerned about home safety, I would hate to think that if we had a break in that I don't have an adequate weapon to protect you." You see, plant the seed.
Then that evening put the movie Cape Fear in the DVD. That'll scare the bejesus out of her and she'll realize that a gun purchase is required.