Must 've been 1987 iirc (Im born in 1978) and I was playing Beyond Dark Castle (still has a busy forum up) that summer on my Mac Plus. For some reason my dad was doing business with Japanese people and closing the deal required a family dinner with them. He challenged me to practise eating with chopsticks, and the stubborn kid I was I practised a lot in the forthcoming days, to the point where I could multibox chopsticks, 2 in my left and 2 in my right hand. And the Japanese were very impressed with my skills, I don't remember if the deal was closed or not, I only remember the constant stream of jokes from my parents at the expense of the Japanese later on, so I guess not.

We had a newer and an older mac plus at that point at home, and since I was so good at Dark Castle, the chopstick experience gave me the idea to try and play the game with my left hand instead of my right hand. as an extra challenge. Shortly after I tried to play on 2 different computers, which was my very first experience with multiboxing games.