I am naughty by nature, but I'm actually not down with OPP. Surprised? Well, OPP has a different meaning to me. OPP means this: A bisexual female/heterosexual male couple are discussing polyamory, but he doesn't like the idea of her fucking other guys. So he says, "Okay, you can sleep with women—but no other men." Sometimes they'll just leave it at that: She'll get him plus her girlfriends, but he'll remain monogamous. Often, however, the next sentence out of his mouth is "And if you get to sleep with other women, then so do I." This is what polyamorous people refer to, disparagingly, as the One-Penis Policy.
Why disparagingly? On the surface, the OPP sounds equitable: Both partners get to do exactly the same thing. Only it's not. It's about as fair and balanced as Fox News. Under the OPP, the straight man is free to pursue any woman he wishes, while his bisexual partner must limit her choices because of his fears.
And fear is the reason for an OPP. Fears like: If another man fucks "my" woman, he'll steal her away. Only by isolating her can I keep her. Men who fuck lots of women are studs, but women who fuck more than one man are dirty whores; my partner cannot be a dirty whore! (Sex with other women, though—that's different. If there's no penis, then it's not real sex, merely foreplay for me.)
Fear of the woman getting an STD from a new male partner is often mentioned as additional justification—which conveniently ignores the fact that straight men can get STDs from women, and thus the One Penis is also capable of bringing one home. Also implied is that a vicious, Highlander-esque competition for status and dominance is biologically inherent to men. They can't help it; it's just their nature. A good, loving woman restricts her sexuality so she doesn't tarnish her man's image and rouse his inner beast.
Women in this position often reluctantly accept the OPP as a stepping-stone. In time, she thinks, he'll relax the rule and let me have sex with other men, too. But it's a rare individual who willingly gives up an arrangement where he gets everything he wants and nothing he doesn't. If you want the freedom to have sex with other men, then work out the jealousy issues in some other fashion. But don't adopt the OPP, because it builds resentment and the temptation to lie.
Male practitioners of the OPP say, "It's not unfair! She doesn't want to fuck other men." If she doesn't want to, obviously she doesn't have to. But why have a rule forbidding it? Lift the gender ban and let her choose as freely as you do. Or stay monogamous and let OPP stand for One-Pussy as well as One-Penis.