he, she, etc. couldn't punch his, her, etc. way out of a paper bag

couldn't punch (one's) way out of a paper bag

Is extremely weak, ineffectual, or incompetent. You want to fight me? You couldn't punch your 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, punch, way
Farlex Dictionary of Idioms.

he, she, etc. couldn’t ˌpunch his, her, etc. way out of a paper ˈbag

(informal, humorous) a person is so weak, shy, etc. that they would never dare react forcefully to something: You don’t need to worry about what Jim would do; he couldn’t punch his way out of a paper bag.
See also: bag, of, out, paper, punch, way
Farlex Partner Idioms Dictionary
See also:
  • couldn't punch (one's) way out of a paper bag
  • can't punch (one's) way out of a paper bag
  • can't punch one's way out of a paper bag
  • can't punch (one's) way out of a wet paper bag
  • couldn't fight (one's) way out of a paper bag
  • couldn't fight your way out of a paper bag
  • couldn't fight (one's) way out of a wet paper bag
  • weak sister
  • a case of the blind leading the blind
  • case of the blind leading the blind