How many feminists does it take to change a lightbulb?
As many as you like. They can’t change anything.
The joke plays on the stereotype that feminists are ineffective at making real change, implying they are only capable of talking about it and not actually achieving it. It's a play on words using the literal act of changing a lightbulb and the metaphorical idea of changing society.
Feminist
Just very very sad for you.