From Why Daniel Tosh’s ‘Rape Joke’ at the Laugh Factory Wasn’t Funny - The Daily Beast:

Tosh says he was joking. Comedians make rape jokes every day, so why is this one getting so much attention? Because Tosh was more than “just kidding.” He was angry. His “joke” was reactive to the so-called heckler who called him out in front of an audience. He used humor to cut her down, to remind her of own vulnerability, to emphasize who was in control.