In some ways I suspect that labeling oneself bisexual may be more difficult than labeling oneself either gay or straight.
Why? Because bisexuals end up having to define themselves a lot more. What I mean is that while "gay" and "straight" denote specific sexual preferences, they also define lifestyles & sub-cultures, at least broadly. I've had a lot of trouble with the term bisexual in my life...and I've only recently realized that the reason I have so much trouble with it is that it isn't enough information.
My best friend labels himself bisexual. That's always bugged me, because his lifestyle and culture are that of a straight man. All of his relationships have been with women, and men have only been playmates. Now, technically, he IS bisexual (sexually oriented toward both sexes per www.m-w.com), but from my dyke-cultured perspective, he's a dabbler, someone who might use gay men as toys, but never take them seriously as life-partners (did someone say bi-phobia*???). Technically, I am myself bisexual...as the definition says nothing of prevalence, merely that one is sexually oriented toward both sexes. I'm about 70% more likely to sleep/date/fall in love/be in a relationship with a woman than with a man.
But culturally, I'm a dyke. That doesn't mean, to me, any of the stereotypical things...it means that the language of sexual signals that I understand is that of lesbians dealing with other lesbians. I've sometimes been told that straight or bi women have been flirting with me (often by those same women, at a later date), but it totally goes over my head, because it's in a language I don't understand. So to speak.
Since my association with my best friend (going on three years, now), I've been working hard to overcome my negative preconceptions of bisexuality. Nowadays, when someone claims to be bisexual, my first response is "bisexual what?" Bisexual player? Bisexual monogamist? Bisexual polyamorous? Bisexual slut? Are you a bisexual who considers zirself monogomaous, but that means to you that you are loyal to one person of each sex? Are you a bisexual with a primary partner who is looking for hookups (be that sex or relationship oriented) but your primary partner doesn't know? Does know? Looking for threesomes as a couple? Bisexual with a primary partner, but looking to play with others (which is, in my opinion, different from polyamory...but that's a whole other post)? Bisexual opens a whole realm of curiosity for me, because I can find no reasonably accurate cultural assumptions to make about it.
Certainly those are questions that can be asked of anyone; bisexual, gay or straight. But I've found that with both the straight and gay communities, that certain assumptions about those options exist until spoken or proven otherwise. The same is not true of bisexuals...or if it is, the assumptions are very different.
Damn. Nothing's simple, is it?
*Since phobia means an "unreasonable fear" of something, I want to clarify what I mean by bi-phobia. I don't think it's unreasonable to fear the possibility of a self-identified bisexual behaving the way I mention above. It's a fear based on many years of experience. What is unreasonable is to assume that everyone who self-identifies as bisexual will behave that way. That way lies bigotry.