I am a nurse. I was lucky to work at and old peoples home when I first came to America. As my English was poor， my aim at that time was to do more but speak less. One day I gave an old lady， Linda， her medicine. Linda was over 90 years old suffering from aged dementia.I tried several times， but Linda refused to open her mouth.Feeling anxious，I said without thinking.

“Linda， open your big mouth.”Unexpectedly， Mrs Linda got angry and shouted，“You have a big mouth. Leave me alone！” I was dumbstrucked and did not know where my mistake laid.

Later on a few pointers from others made it clear to me that “big mouth”： in American slang refers to a person who talks too much and spreads sercets around. No wonder Mrs Linda got angry when she heard what I said. Acturall， I should have said： “Open our mouth wide.”