4. Your masturbation frequency
Women know that guys masturbate. It's a fact of life. But your woman doesn't need to know the frequency, duration and tools that you use to get off — it might just pique her curiosity. A guy wants to be alone when he's playing with himself, and you don't need her trying to sneak up on you when you're having some "personal time."
3. Your ex-girlfriend memorabilia
You might have kept naked pictures of your exes. Maybe you've stashed away their love letters or their panties. Heck, you may have a whole database of their names and personal info in an Excel spreadsheet. Whatever the case, never let your current squeeze find out about your memorabilia. Even if she's willing to leave the past in the past, you can bet that she won't balk at dropping their names as ammo in future fights. For example: "I see then. I guess Melissa would have never done that, would she?" Get the picture? Besides, these are your private memories — your new girl just doesn't need to know.
2. Your embarrassing moments
We've all had them. And I'm not just talking about light embarrassment, like farting in public or getting caught in a Freudian slip. I'm talking about severe, crippling embarrassment, on the scale of soiling the sheets or having an ex post an indecent picture of you online. If you've suffered this kind of monstrous humiliation, she should not get a whiff of it. The idea of it and the accompanying visual will surely blow your cool factor right out of the water, and leave your woman killing herself with laughter. It's not the best way to remain slick, and there's a good chance that she'll never look at you in the same light again. You've already lost your pride once over the incident; there's no need to relive the experience.