The term 'men who have sex with men' (MSM) as commonly used by HIV/AIDS researchers and policy makers is said to describe an obvious group of men. Or does it? While MSM disrupts the homosexual/heterosexual dichotomy through focusing on sexual practices rather than sexual identity, it remains entrenched in binary understandings of sex and gender. Influenced by queer and trans theories, a genderqueer methodology is employed to examine what discourses are deployed when MSM are categorized as a seemingly homogenous group. Who are the “men” in MSM and what are the material consequences of MSM discourse in HIV/AIDS work? Guided by feminist poststructural and Foucauldian theories, this study highlights how MSM discourse functions to exclude trans, intersex, and other non-normative sexed and gendered people while considering the potentially deadly effects of this discourse on those outside of MSM categorizations particularly focusing on its use in the Canadian Guidelines on STIs.