a person who has sexual relations with both sexies but are not monogamous with either sex. May be someone who participates in orgies and open relationships. Or may be a ninfo.
a heterosexual who is interested in, and may want to try intercourse with someone of the same gender, but they are not entirely sure if they are bisexual or not
a breeder who at present is straight but has latent homosexual inclinations.
Usually female breeders that are up for a bit of elbow rubbing at the request of their boyfriends.
seetrendsbian
Guy (or girl) who is sexually curious, not necessarily due to sexual preference, but rather due to environment, peer pressure, predominance of alternate lifestyles in immediate surroundings. (From the adage "Monkey see, monkey do.")
"That bi-curious george is only interested in a quick one-night stand before going home to bone his girlfriend."