《笑林广记·古艳部》
某日妾打算拜见妻，与丈夫商量应怎样写帖子，丈夫说： 该用 寅弟 二字。 
一日，妾欲谒妻，谋之于夫： 当如何写帖？ 夫曰： 该用 寅弟 二字。 
One day, the concubine planned to visit the wife and asked her husband what to write on the invitation. The husband said, "Use the words 'Yin Di' (Junior Tiger)."