Forbidden Words

My Innocent ESL Student: "What is meaning the word ....set... Teacher Betty?"
Me, knowing simple words are hardest to define quickly pulls up the Oxford English Dictionary while talking: "Well, you see, the English word set means..."
Me: Sees 430 separate definintions and a 60,000 word explanation.  
Me:....
Me:...
Innocent ESL Student:  "Teacher Betty?" 
Me sweating: "means something very offensive. Never ask me or any other teacher that again. Now moving on....