Fail in official examinations

In the Song Dynasty (960-1279) there was a joker called Sun Shan. One year he went to take the imperial examination, and came bottom of the list of successful candidates. Back in his hometown, one of his neighbours asked him whether the neighbour's son had also passed. Sun Shan said, with a smile: "Sun Shan was the last on the list. Your son came after Sun Shan." 

宋朝（公元960-1279）时有一个擅长幽默的人，名叫孙山。有一年，他去参加科举考试。榜发出来，孙山考上了最后一名。回到家乡，一位同乡向他打听自己的儿子考上没有。孙山笑了一笑说：“孙山考上最后一名，您儿子的名字还在孙山后面呢。” 

Later, people used this idiom to indicate failing in an examination or competition. 

后来人们用“名落孙山”来比喻考试没有考上或者选拔没有被录取。