The whole article is here, and it is written by Harriet J, whose whole blog is worth reading.
Here are just the highlights, for those who want the sparknotes version:
You are told a rape joke. These are your options:
"Run with the rape joke! Make it even more rape-y! Now your friend will never guess you have been raped. Bonus prize: if he ever finds out, he will respect you for not making a “big deal” out of your rape"
"Say Nothing. Hate yourself for saying nothing. ... Hate your friend, because he doesn’t know that every woman he knows has been raped. Have minor flashbacks of what was done to you. No feeling the sun, the breeze now, just his hand on your shoulder to get leverage."
"Initiate a Very Serious Conversation, out of nowhere, like. Tell your friend that joke was not funny. Tell him rape is never funny. Keep talking after his face has pinched up in resentment and disgust, because you are RUINING his day and his BEER and his FUNNY."
"Follow version one, except also disclose to your friend (who thinks rape is funny and exciting) that you have been raped. Be surprised, all over again, that this does not immediately change his perspective ... Wonder if he has raped, without knowing it, because it was just a concept. ... After this, will he now tell everybody that you FREAKED OUT just because you were apparently “RAPED” and you can’t GET OVER IT when it was just a JOKE, SERiously? Will everybody know you have been raped? Will everybody think you are a humorless rape-bot from now on?"
The article. go read it. Reading it makes me unhappy all over again - and I guess that's my endorsement of it. I'm not going to comment too much on what's written above except to say that it's true, and it's a decision you have to make in an instant, because the conversation will move on like nothing happened and that whatever you do you will feel like shit, and somehow, somehow that will turn into your fault.