Is a threesome in your future? Whether it's with your lover, a fling, or your husband/wife, the fantasy of a ménage à trios has crossed the mind of many at one point or another, and this week at Good in Bed, I’ll be answering questions and talking about the role fantasy plays in stimulating desire.

Not everyone is open to it, but you’ll be happy to know that many (men and women) have fantasized about it.

Unfortunately, most fear judgment by their partners, making them too embarrassed to bring it up. Sometimes, when we hear our partner has a threesome fantasy it’s easy to feel emotionally hijacked and react brashly. To get beyond this, affirm their desires, assure them that their fantasies don’t depreciate their value long-term, and appreciate their openness to experience new things. In fact, any time I’ve had a partner approach me with the idea, I’ve taken it as a positive indicator of their comfort-level with me, regardless of whether I was willing to partake.

An important precursor to threesome talk is twosome talk. If you can communicate openly about other things sexual, this kind of discussion will be far less daunting. A really viable first step is to enjoy it as a sexy fantasy – talk about what's sexy about it, pretend you're going to have one and pick out people from a crowd. Make it a sexy secret between you and your partner; it doesn’t have to go farther than this to be a real source of sexual stimulus. Based on their reaction, you can determine whether it’s something you should bring up seriously or not. If they don’t show any inkling of interest, leave it as a fantasy, and incorporate it into a less risqué avenue of excitement (for example: sex toys, porn, or role-play).

If it sparks interest, you can get into the details of how each of you might envision it happening; at which point you’ll know whether they’re interested in a female or male guest-star. Not surprisingly, around 95 percent of heterosexual men prefer to have a woman join in. However, women tend to vary in their preferences. I know some straight women who cringe at the idea of another woman with their man and would prefer a male guest star, where others would actually choose to invite another woman. The thrill of a threesome may come from watching it happen, participating in it, or a combination of both. You need to talk about these things to figure out your preferences.

If you get to this point, establishing ground rules is an important next step. Research on women shows they tend to be pretty protective of their emotional bond with you. Take note that if the third party threatens that bond in any way, the night will be over (and so might your relationship). You should discuss whether any rules apply to kissing, penetration, etc.; this is crucial to the successful launch into this fantasyland.

Also, discuss all potential outcomes with your partner, so you both know what to expect once it’s over. Remember that you have a history and a future with your partner, and they need to be the star of the show. Never push them into something they aren’t sure about; if the decision isn’t entirely mutual, it has the potential for disaster.

Although research suggests that threesomes tend to occur most often in casual sex settings, now more than ever folks in serious relationships are becoming open to inviting a third into the bedroom to keep monogamy from becoming monotonous. We are surrounded with messages that encourage us to ‘mate for life’, making this an incredibly potent fantasy. We tend to be attracted to things that are risky, and this fantasy encompasses so much of that risk it becomes rather alluring.

Communication, an open mind, and a mutual sense of security in the relationship are all you need to make this sexual adventure one to remember.

Kristen Mark, M.Sc., is currently completing her Ph.D. in health behavior with concentrations in human sexuality and statistics at Indiana University. She is an associate instructor for health and human sexuality courses at I.U., and is a project coordinator at the Center for Sexual Health Promotion. She is a writer for Kinsey Confidential, a sexuality-information service designed by the Kinsey Institute for Research in Sex, Gender and Reproduction. For more of Kristen, please visit Good in Bed.