You can only mask outrageous things as humor if they are so utterly outrageous as to be virtually unthinkable. If they become only slightly plausible, they become no longer funny. Therefore, if jokes about murder are no longer funny, it’s because people no longer believe that murder is as likely to be unthinkable as it used to be.

This is why I think that masking outrageous things as humor is a losing strategy. Either it is funny, in which case the thing being masked with humor is so outrageous as to be completely niche, making the secret signal irrelevant, since so few people recieve it. Or, the thing is such a relatively common stance to make it no longer absolutely unthinkable, which makes it no longer funny, which removes the mask.

(Also, how do “white supremacists” fit into this? The original joke was about murdering an ex-girlfriend. This might possibly be generalized into misogyny, but I fail to see the connection to white supremacy. Please don’t fall into thinking that all people who hold opinions which you don’t like also hold all other opinions which you don’t like.)