Depends. More details are required here. Right now I have no idea what you're asking about, so be more specific with the details.
For example: Who's the comedian? Is he a big one? Local?
A friend? Where did the joke appear? Stage performance?
TV episode? Movie? Is the joke scripted?
Published? Copyrighted in any way? What are you going to do with the joke?
Use it in a dialogue or base a whole screenplay on it? Is the joke's author (the comedian or someone else who holds the rights to it) dead? If so, for at least 70 years?
What are you going to do with the screenplay? EDIT: Then you can't. You can, however, write down the screenplay for fun and put it in the drawer.
You can't sell it, that's for sure. But you can use it as practice. Speaking of not knowing much about how Hollywood works, one doesn't just write a screenplay and then sells it, if that's what you're thinking.
That's not how Hollywood works. We're talking about a very complex and complicated path, and the vast majority just don't get to that point or even close to it. In general, it would take you several screenplays and years of very hard work just to get to the required level... And then you would need an agent or a manager.
And since newcomers rarely sell, you would probably need to get some experience first... What I'm saying is, since it takes 3-20 years of hard work to get to the point where you can finally try (to secure representation, and then try to sell), and since it basically takes you pursuing screenwriting as a career... you wouldn't even try to sell this one. Maybe your 10th. Maybe.
And 10 years from now - if you're lucky. And IF you get to that point at all. Either way, if you're interested in a screenwriting career, then you're gonna have to write your own material.
Screenplays don't just sell themselves, they sell you as a writer. If you're not going to pursue that, then again, write whatever you want, for fun, and keep it in the drawer. Otherwise, you'd be taking a risk.
Ask yourself what you want to do exactly and how much you're willing to sacrifice.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.