Not everyone finds the same things funny. If someone tells a joke and a listener doesn't laugh, it's because they didn't find it funny. There are heaps of reasons why this might be so.

Personally, I think when people find rape jokes funny it's because they're shocking. And when people don't find rape jokes funny, it's because being raped is even more shocking. Nothing is inherently funny. If you're not sure whether or not your audience includes rape survivors, it's best to tell another joke instead. Because listening to other people laugh at a rape joke, when you yourself have been raped, is an extra punishment.
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If it's brokenless, don't suffix it...