A "good" girlfriend is a great person to be in a relationship with. She's ideal for movie dates (always shares her popcorn) bouts of illness (shows up with chicken soup in the pouring rain) and when you want to complain about your job (agrees you're so undervalued here).

But all that goodness can sometimes come with a downside. In the bedroom.

She undresses only under cover of darkness. She balks at revealing lingerie. Her sexual repertoire is limited to only one vanilla position. And you're afraid she'll have a stroke if you break out a battery-operated toy.

If your lady is conditioned in the mold of "good girls don't..." it's your job to unleash her inner bad girl. Try one of these sneaky moves to push her in the right direction.

Naughty Girl Nudge #1: Start with low stakes.

How do you get a good girl to lose a few inhibitions? You need ways to get the thrill of doing something a little crazy, but without scaring her off or making her feel cheap. She would recoil if you show up to bed with the digital camera, but a mirror can up the naughty ante to otherwise "nice" sex. Prop a big one - full-length is ideal - up by the bed and you can both enjoy seeing yourselves, and each other, in the throes of passion. Call it exhibition-lite.

Naughty Girl Nudge #2: Make her dreams a reality.

Did she kid around about going skinny-dipping? Find her a lake. She's expressed an interest in burlesque? Buy her something sexy to shimmy out of. Helping her conquer her fears will build trust - making her more likely to be daring in the future. If that sounds outside her comfort zone, start small. Invite her to share one of her little fantasies (oh, she has one), then ask her to close her eyes while you tell her the story. Include as much detail as possible and put your hands to work. She'll be more likely to share such fantasies again once she sees how willing you are to turn them into a reality.

Naughty Girl Nudge #3: Play with control.

She'll find it hard to resist you if you show her, well, that you think she's irresistible. Surprise her one night by taking charge - the whole hair-grabbing, pinned-down, have-to-have-you now thing. She may find it easier to totally let go if she's under your "control." Turning the tables - by putting her in complete control - can have a similarly delicious effect. Many women are too shy to call the shots, so give her a little encouragement that you really want her to have her way with you. The invitation may be all she needs to let go of a few inhibitions.

Naughty Girl Nudge #4: Try reverse psychology.

If you suspect that beneath the shy exterior of your librarian-like girlfriend beats the heart of a man-eating temptress, you might try a little reverse-psychology. Say something like, "There's this thing I've always wanted to try, but you're such a nice girl I don't know if I could even suggest it to you." Yeah, it's a prick move to imply she's too boring for you, but if she decides to prove you wrong, doesn't everyone win?