Fig. able to do something very easily, possibly without even looking. (Able to can be replaced with can.)Bill boasted that he could pass his driver's test blindfolded.
Also, do standing on one's head. Perform very easily, as in Dave said he could do the income tax return blindfolded, or An excellent carpenter, he could do just about anything standing on his head. For a synonymous hyperbolic expression, see with one arm tied.