"Yata group" is "야타족"(ya-ta-jok) in Korean.
It is compound word of 야 (Ya/Hey) + 타 (Ta/ "Hey, ride!"). It is made from the fact of man who tempt the woman in the car, and it came to be called 야타족 (Yatajok). Orange group (in the 90s 오랜지족 words that were popular with).