《笑林广记·形体部》
有个结巴到街上买桐油，他对店主说： 我要买桐桐桐  油 字怎么也说不出口。
来到市中买桐油，向店主曰： 我要买桐桐桐 油字再也说不出口。
A stutterer went to buy tung oil on the street. He said to the shopkeeper: “I want to buy tung tung tung oil.” But he couldn’t say the word “oil.”