What is this actually a picture of? I don’t get the joke.

I believe that’s R. Budd Dwyer; he’s pulling a revolver out of that envelope just before shooting himself in the head.

Trump doing that would be dark?

we still joke how Hitler wasn’t that bad, because by the end he killed Hitler.

The difference is that Dwyer did it on live television, in a highly publicized press statement. Cameras didn’t cut away.