The first message ever sent over ARPANET was meant to be 'LOGIN' — but the system crashed after just 'LO'.

1969

UCLA student Charley Kline was trying to log into a computer 350 miles away at the Stanford Research Institute on the night of October 29, 1969. He typed L, then O, both confirmed received — then the receiving system crashed on the G. He rebooted and finished the full login about an hour later, but 'LO' had already become, by accident, the first word ever transmitted over the network that grew into the internet.