(as) clear as mud
US /əz klɪr əz mʌd/
UK /əz klɪr əz mʌd/

1.
전혀 이해할 수 없는, 매우 불분명한
very difficult to understand; not clear at all
:
•
His explanation of the new policy was as clear as mud.
새 정책에 대한 그의 설명은 전혀 이해할 수 없었다.
•
The instructions for assembling the furniture were as clear as mud, so I had to guess.
가구 조립 설명서는 전혀 이해할 수 없어서, 그냥 짐작해야 했다.