"아웅" is a word which imitates a cat sound. Actually the sound in Korean is much closer to "야옹" but "아웅" is used as a part of proverb. A verb(하다) is added on it, so "눈 가리고 아웅하다" means someone covers the opposite's eyes, then makes a sound like a cat. In real, he/she is not a cat, tries to deceive the opponent eventually it's no use doing that. When people is going to cheat or lie, you'd say the proverb.