In “no, duh” news, several new studies reported by the New York Times show that bisexual men actually exist.
One of the most common biphobic narratives is that the penis is what counts. A woman who has sex with men is really straight, even if she also fucks women; a man who has sex with men is really gay, even if he also fucks women. If a man fucks a man, even once, he is forever corrupted from the heights of heterosexual masculinity. It’s the new One Drop rule. (Comments that explain this using femmephobia and/or the view of male sexuality as inherently degrading get a cookie. Comments that explain this using some mechanism I haven’t thought of get infinite cookies.)
It is also interesting to note that the studies cited in the New York Times stopped with that “judging heterosexuality by showing lesbian porn”, since I personally think it is extremely weird to clinically define male heterosexuality as the condition of being a man turned on by two lesbians doin’ it.