On pornographic websites it's common to find a category dedicated to threesomes; but not all male-female combinations are present there. Threesomes in which males engage in sexual activity with other males are segregated to a “Bisexual male” category. The same is not true for females.
This follows a world view where female bisexuality is something that is promoted and expected, while male bisexuality is demeaned and rejected from the “normal”1Breanne Fahs, “Compulsory Bisexuality?: The Challenges of Modern Sexual Fluidity”, Journal of Bisexuality, no. 9, Issue 3–4 (2009): 431–449.. The organizing system lays a narrative where same-sex desire between men should be concealed.
