able to (do something) with (one's) eyes closed
Capable of doing something with very little or no difficulty; able to complete or accomplish something in a relaxed, carefree, or effortless manner. It took me a little while to get used to this job, but now I'm able do it with my eyes closed! You should ask Johnny for help—he can do calculus with his eyes closed. I used to be able to parallel park with my eyes closed, but I'm so out of practice now that I don't live in the city anymore.
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