《笑林广记·腐流部》
晚上先生教对子，正巧庭院中栽有梅树，于是指着说： 老梅。 
师出夜课，适庭中栽有梅树。即指曰： 老梅。 
In the evening, the teacher taught the students to write couplets. In the yard, there was a plum tree. Pointing at it, he said: “Old plum.”