Donald Trump doesn't laugh. Perhaps this is an urban legend, like the Tijuana rat someone mistook for a stray dog (I've known two separate people who swore that it happened to a friend of theirs). Or maybe, like the devil trying to quote scripture, whenever Trump tries to laugh it catches in his throat and he gags on it.
Trump has a smile, after a fashion, that looks more like a colicky baby than a mirthful human. But the search for a Trump laugh is the snipe hunt of politics.
Trump does find a kind of joy in being adulated. But, like a crack addict, no praise is strong enough nor lasts long enough to be truly satisfying. Then there are the long hours when everyone is trying to work and don't have the time to tell Trump how smart he is or how big his hands are.
So Trump spends an inordinate amount of time publicly praising himself. He'll tell anyone who'll listen, and everyone who tries to not listen, how smart he is, how he has the best brains, how he is a better general that any actual general, and how he has never made a mistake in his entire life and so never has had to apologize. And when something does go wrong it is always somebody else's fault.
Like laughter is contagious, Trump's mirthlessness is also catching. By accounts, Sean Spicer once had a pleasant sense of humor. But after just a month as Trump's chief spokesliar, Spicer has lost his ability to laugh. Spicer is now a bitter, paranoid shadow of a man, a Capt. Queeg determined to root out imagined traitors through his geometric logic.
Spicer even held a press briefing exclusively for alt-right outlets who spent the time showering Spicer with praise instead of questions.