Egyptian judoka Islam El Shehaby has been sent home by the International Olympic Committee for refusing to shake the hand of the Israeli who beat him. "Judoka" is the word that the martial art of judo uses for its practioners, the way fencing calls its competitors "fencers."
Israeli judoka Or Sasson beat El Shehaby in the 100 kg division on his way to a bronze medal (the 100 kg division is judo's heavyweight class). Judo etiquette requires the two opponents to face each other and bow after the match is over, and handshakes have become customary although they are not required. El Shehaby would at first do neither, and had to be called back to the mat more than once before he would bow as required. The Rio crowd booed him, especially when Sasson stepped forward, hand extended, and El Shehaby backed away shaking his head.
Even though the tournament is over and El Shehaby had already lost anyway, the IOC's punishment is not the complete shoulder-shrug at the incident one usually expects of them. His sport's international governing body will doubtless take a dim view of his actions, he has been evicted from the Games and he will not be able to march with his fellow Egyptian athletes in the closing ceremonies. While we might wonder if that last bit is really all that much of a punishment, we should remember that representing one's country and participating in the closing ceremonies is not the mind-numbing bore that watching them on television usually is.
(Edited to correct "judoku" to "judoka" throughout)