Below is what actually happened in a Chinese middle school.Enjoy!
Situation 1, in class.
X: My watch is accurate. It's 12.02. I'll stop teaching, and then we can go for lunch.
Y: No, we must wait for the bell to ring.
X: Maybe the bell ringer has fallen asleep,he's getting on in years,you know.
Y: Stop making stupid jokes. Your jokes aren't funny!
X: I must be going now.See you.
Situation 2, on campus.
Y: I must ease myself.You go to class alone.
X: What do you mean?
Y: My American FT at university told me it means that I must go to the WC.
X: You should say relieve instead of ease;maybe your listening is on the poor side.
Y: No,you don't know American English.
Situation 3, in class.
X (to students):You can say 'go to the movies' instead of 'go to see a movie'. It's shorter and better.
Y (to X in front of the class): You should say 'go to movies'.You needn't use 'the'.
X:(to Y in front of the class): You should trust me. But if you don't you can look it up in an advanced dictionary. It never lies!

X is a rather old non-American male, a native speaker of English only with a maths degree and a teaching qualification in maths and physics, username Turino,

Y is a haughty, but beautiful, recent Chinese university graduate without a sense of humour whose English is dodgy, trying to be a teaching assistant.In my view, only good at befriending gullible students and reporting on my shortcomings to her stingy Chinese bosses for a low salary, someone I can well do without in class!