Two factory workers are talking

The woman says: "I can make the boss give me the day off."
The man replies: "And how would you do that?"
The woman says: "Just wait and see."
She then hangs upside-down from the ceiling.
The boss comes in and says: "What are you doing?"
The woman replies: "I'm a light bulb."
The boss then says: "You've been working so much that you've gone crazy. I think you need to take the day off."
The man starts to follow her and the boss says: "Where are you going?"
The man says: "I'm going home, too. I can't work in the dark."