The punchline comes when he puts on a red “Make America Great Again” hat and the biker gives him a smile and says, “Just be more careful next time, OK?”
But what the out-of-context clip fails to capture is the much larger joke of the episode. If Trump had watched the whole thing, he would realize that Larry is using the MAGA hat as a “great people repellent,” something to help him get out of lunch with a guy who annoys him or to make sure no one takes the seat next to him at the sushi bar.
The bit with the biker is actually the moment the joke gets flipped on its head. Not only does the hat repel most people in David’s Hollywood circle, it also attracts maniacs on motorcycles who would otherwise want to violently attack him.