The Goding (고딩) is the slang of 고등학생 (go deung hak seng, high school students).
Also I use the word 고삐리 (Gobbiri).
<Slang expression of student>
-elementary students "초딩 Choding, 초등학생 Cho deung ha seng" , junior high school students "중딩 Jung Ding, 중학생 Jung hak senf" and high school students is "고딩 Goding, 고등학생 go deung hak seng " - college students "대딩 Deding, 대학생 Dehaksen "