Threatening the president of the United States is a federal felony under United States Code Title 18, Section 871. It consists of knowingly and willfully mailing or otherwise making "any threat to take the life of, to kidnap, or to inflict bodily harm upon the president of the United States". https://www.washingtontimes.com/news/2019/jul/31/how-menacing-invective-against-trump-creates-dange/

GOOD FOR JOE BIDEN

First and foremost, saying that you could have beat someone up in highschool is not a written threat of bodily harm as outlined in Title 18 sec 871. Secondly, that's not something someone should say, especially someone who hopes to be the president, as it is extremely immature and shows little diplomacy. Thirdly, Biden couldn't take Trump in a fight anyway. Fourthly, Trump made very similar vague non-threatening threats about Obama back before Trump was president, so they are both trogladytes. Fifthly, either way, one of them will be president in January, so we will all suffer as Americans, because of this mess. I 100% blame the GOP for putting the more ignorant and brash president in office that the nation has ever seen. And I blame Democrats for giving us the just-as-bad option of Hilary Clinton and now Joe Biden who talks like he wants to fight with everyone who wants to ask him a question, yet he can't seem to remember where he is or what he's doing anyway. We are up a creek. Lastly, as mess up as this country is at the moment, it's still a heck of a lot better than moving abroad and dealing with even bigger messes that comprise the politics of foreign countries. So, I guess you could say that humans are all up a creek the world over.