英語のgeeck、geek、foolから。やがてオノマトペから、半日言葉を保てず、のどをせき込む音。
"An ordinary geek doesn't actually eat snakes, just bites off chunks of 'em, chicken heads and rats." [Arthur H. Lewis, "Carnival," 1970]By c. 1983, used in teenager slang in reference to peers who lacked social graces but were obsessed with new technology and computers (such as the Anthony Michael Hall character in 1984's "Sixteen Candles").
geek out vi. To temporarily enter techno-nerd mode while in a non-hackish context, for example at parties held near computer equipment. [Eric S. Raymond, "The New Hacker's Dictionary," 1996]