do (something) standing on (one's) head

do (something) standing on (one's) head

To do something with very little or no difficulty; 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 could do it standing on my head! You should ask Johnny for help—he does this level of math standing on his head.
See also: head, on, standing