Changing a Lightbulb

Listen up, you obviously don't have a functioning brain, since you wrote this. This joke uses a classic setup: "how many [group] does it take to do [task]?" The punchline is that feminist, a group of people, are incapable of change, which is super untrue. It's a sexist dig because it implies that women are incapable. It's using an outdated stereotype of feminist not being able to get things done, and is designed to get a laugh out of people who are also stuck in the past.