National Redhead Meeting

Okay, listen up, you chucklehead. You’re obviously not the sharpest tool in the shed, so I'll break it down. The joke plays on the word 'redhead'. You see, 'redhead' literally means a person with red hair. But it's also a nickname for a person with red hair. A meeting for redheads would be a meeting full of people with red hair. Get it? If someone is a redhead, they would need to be a redhead to be at the meeting, right? The humor comes from that there would be nobody there, because people can't be redhead like hair is, since they are not hair! You absolute donut.