couldn't fight (one's) way out of a paper bag
Is extremely weak, ineffectual, or incompetent. You can definitely beat that scrawny kid—come on, he couldn't fight his way out of a paper bag!
couldn't fight your way out of a paper bag
If someone couldn't fight their way out of a paper bag, they are very bad at fighting. They are no use to you as allies. They couldn't fight their way out of a paper bag. Note: You can replace fight with other verbs that state what someone is not able to do. Not one of these actors could act their way out of a paper bag.