Jezebel has a decent article about the whole Daniel Tosh thing. (The aforementioned link will explain it if you have no idea what I'm talking about, but long story short: Daniel Tosh made some jokes about rape, got heckled by someone saying rape is never funny, and then made a "joke" about her getting gang-raped.)
I think the Jezebel piece is more or less spot on, but I think the entire article could have been more succinctly written as "be funny". Yes, "only make jokes about rape if they are mocking rape culture and not victims", but that's only one way to go about it, and it's just another way of saying what's important. Which is: be funny. Simply riffing on rape for shock value is not funny, unless you're a developmentally-disabled 13 year old misogynist in the making. They especially whiffed on their justification of Louis CK's joke, which basically boiled down to "well, Louis was making jokes about rape here, but he's funny, so we know he doesn't mean it."
Daniel Tosh's crime wasn't that he made a joke about rape, it was just that he wasn't funny, which is forgivable. Beating the dead horse of the bit and being hostile to a heckler? Maybe less forgivable.