In addition to silly, stupid, there are things to do without thinking, reckless, reckless meaning.
Shan Cannon originally for the Northeast "beard" (bandits) jargon, when the cannon is very popular, the bandits got some of the cannon, second-hand guns, but the quality is not good; even if the quality is good, the level of the gunner is poor, so there is always a cannon is not allowed to hit the time.
Over time, people collectively call these cannons mountain guns, and the bandits also use the mountain run to joke among themselves. Someone who didn't get things right, or didn't think things through, or did something stupid, or had outdated knowledge (not new knowledge, but second-hand), or was dressed in outdated clothes, were all called mountain cannons.
In the 1920s, Mr. Zhang Xueliang, as the highest administrator of the Northeast, and Commander-in-Chief, vigorously implemented educational reforms, and with the support of the strong economy of the Northeast, national celebrities, and even foreign professors gathered in Fengtian (Shenyang). Many generals from bandit background had to be re-educated. Mountain guns and other vernacular languages were gradually lost