For the record, I don’t believe the ubiquity of prison rape humor disproves the existence of rape culture, but rather proves it. Zek J. Evets writes at the Good Men Project:
I knew a teenage girl who refused to believe men were capable of being raped by a woman. When I told her the stories about Mary Kay Letourneau, Debra Lafave, and certain Zimbabwean women who even went as far as to steal semen in addition to gang-raping men. She said to me, “that doesn’t count.”
I’ve known grown men who are more likely to believe in UFOs or Bigfoot than some woman who says she was raped. (For the record: UFOs and Bigfoot are real.) They laugh at these women’s stories and slap each others’ backs while calling themselves “good Christian folk”.
Unlike almost any other crime, rape is one in which our private notions of gender, sexuality, and personal responsibility become politicized to the point of oppression.