what does 원펀치 쓰리강냉이 mean?
I believe that 원펀치 is (One punch) and 쓰리 is (three)
But 강냉이?

Question

what does 원펀치 쓰리강냉이 mean?
I believe that 원펀치 is (One punch) and 쓰리 is (three) 
But 강냉이?

Answer

강냉이 is the folksy term for corn.

Here it is used as a slang term for teeth.
You know when a tooth is out of the mouth it sort of looks like a s corn grain.

So it means "One punch and (there's) three knocked out teeth".
A guy swung his punch and the result was three knocked out teeth.