That flyer admits one person only. So don't bring some other guy with you.

根据朗文当代英语词典，flyer在此处意为：a small sheet of paper advertising something

所以

这句台词里，flyer指的是Aaron递给Cady的party invitation，而不是“梯子”。正确翻译应是“邀请上说只能一个人去，所以别带别的男孩一起哟”😉