A condition of emotional paralysis experienced in the days following one's viewing of "Brokeback Mountain."
Biff: "Ever since Jim saw 'Brokeback Mountain', he's been crying in his room and hanging his ex-boyfriend's shirt behind his closet door."
Doyle: "He must be suffering from brokebackitis."
an unknown STD transmitted through the act of gay sex.
jim: whoa phillip, you look sick.
phillip: i feel like shit...i think you gave me brokebackitis last night.