The present study analyses the performative, discursive identity constructions of three LGBT activists who identify as bisexual in narrativas regarding the process of coming-out and biphobic stereotypes, prejudice and discriminations. Bisexual-identified individuals are often little accepted in LGBT movements, despite being theoretically included due to the letter B in the anagram. Bisexuality is treated as just a phase before coming out as heterosexual or homosexual, and bisexual-identified people have to deal with being stereotyped as promiscuous and untrustworthy. This study combines Applied Linguistics, Queer Linguistics, Anthropology, Queer Theory, Bisexual Epistemologies and Narrative Analysis. The data were collected in individual interviews with three bisexual-identified women that participate in an LGBT activism and awareness group in Rio de Janeiro, in which 22 months of ethnographic fieldwork were realized from 2010-2012. The analysis concentrates on the ways in which the three activists construct their bisexual identity performances as permanent and not promiscuous. In these constructions, we shall see (1) how they must prove that their identity performances are not just a phase in order to be accepted, but in so doing reinforce the idea of fixed/stable identities, (2) how their identity constructions reproduce and/or subvert the tendency to define sexuality based on the sex/gender of the person(s) desired, and (3) how the constructions of non-promiscuous bisexual performances exclude and/or open other possibilities for sexual diversity. The analysis shall be used to propose discursive and critical-thinking strategies regarding identity categories that can be further developed with the group’s activists, to encourage the acceptance of bisexual identity performances and of sexual diversity.