I can get (though I don't agree with) Tosh not being funny. But why do we hate rape jokes? Do we hate all "off color" jokes? Or is rape special?
The latter.
Ok. So are all rape jokes unfunny? What if it's a bad person that is being joked about being raped? What if it's so over the top it can't possibly be true, like the aristocrats joke?
Jokes like the aristocrats are categorically distinct, since it's not the
material being discussed that's supposed to be funny, it's the sheer
degree of impropriety (a degree that it's hard to hit correctly). Jokes in which rape qua rape is a figure of fun are unfunny and inappropriate regardless of who the purported victim is.