Always, always punch up. Never, ever punch down.
Never, ever, ever punch down.
Jokes are funny when they mock the powerful. They are not funny when they mock the powerless.
That's why right-wing humor is just not funny at all. In fact, it's why humor is intrinsically left. But the funniest stuff on the left, while it may mock horrid right-wing beliefs, reserves its greatest scorn for the purveyors of those beliefs, rather than the consumers.
Jokes are not funny when they have victims. Some of the tricks played by PR would be funny if they didn't have victims. But they do. They have victims. And so they're not funny.
This may be the most important of all our lessons, ever. It might be the only one that's 100% guaranteed to be useful.