(one's) way out of a paper bag

(one's) way out of a paper bag

A phrase use emphasize that one is particularly dim-witted, unintelligent, incompetent, or unable to do something basic, simple, or straightforward. Jeff's new boyfriend sure says some dumb things. The dude probably couldn't find his way out of a paper bag. Don't assign that project to her, she couldn't punch her way out of a paper bag!
See also: bag, of, out, paper, way