Let me illustrate.
Here is a pretty lame joke, but with a proper delivery:
Person 1: What's the difference between a sandwich and a rabid dog?
Person 2: I don't know.
Person 1: ... I am never asking you to fix me lunch.
Here is the same joke with a similar setup to the girl gamer travesty and B^uckley:
Person 1: What's the difference between a sandwich and a rabid dog?
Person 2: I don't know.
Person 1: You don't know the difference between a sandwich and a rabid dog? So if I asked you for a sandwich you might bring me a rabid dog, instead? I am never asking you to fix me lunch!
If you explain the joke, it has failed.
If you explain the joke before the joke has even finished, it has failed doubly.
Here is a pretty lame joke, but with a proper delivery:
Person 1: What's the difference between a sandwich and a rabid dog?
Person 2: I don't know.
Person 1: ... I am never asking you to fix me lunch.
Here is the same joke with a similar setup to the girl gamer travesty and B^uckley:
Person 1: What's the difference between a sandwich and a rabid dog?
Person 2: I don't know.
Person 1: You don't know the difference between a sandwich and a rabid dog? So if I asked you for a sandwich you might bring me a rabid dog, instead? I am never asking you to fix me lunch!
If you explain the joke, it has failed.
If you explain the joke before the joke has even finished, it has failed doubly.