There are occasions in life when you fail to think far enough ahead, and suddenly discover you've said something you maybe shouldn't have. This is doubly true in teaching. Let me just set the scene:
Place: a general English lesson (aka speaking class)
Discussion topic: male/female communication
We had just read a text by Deborah Tannen in which she uses an example of a man who invited his friend to stay over without checking with his wife first. This upset his wife. Her husband felt that to tell his friend, "I have to ask my wife for permission," would have been emasculating.
This led to a discussion of how the men in the class view their male friends who are always checking with their girlfriends before agreeing to spend time with the guys. My question was along the lines of, "So when a friend says he has to check with his girlfriend, does it make you think he's whipped?"
As soon as the word was out of my mouth, a student asked what it meant, and I replied, "Oh, it means he has to ask permission for everything, it's short for-"
In my head, I suddenly realized what I had done. "Well, I really shouldn't tell you, it's not appropriate for the classroom."
Again, it was the wrong thing to say. And yes, I ended up telling them the whole phrase, while insisting that they not use it in any formal setting. As they (rightly) argued, how else are they going to learn authentic language? I just have to hope they either forget the phrase (right!) or at least never use it in a situation where it's going to come back to me.
Ah, the many surprises inherent in the life of a teacher!