칠칠맞긴 is a short form of 칠칠맞기는( the correct expression is 칠칠맞지 못하기는)
It means "You are indeed clumsy."
* 칠칠맞다 originally means "be neat, tidy"
And 칠칠맞지 못하다 means "be clumsy"
But 칠칠맞다 is recently commonly used as a short form of "칠칠맞지 못하다"
* 기는 is a short form of 기는 하네. It has an emphatic feeling and is used when the speaker realizes, accepts or concedes that a piece of information is indeed correct.