The hardest one, er well the best one i ever had was...
"What is the definition of holding out?"
All of you fellow CFI's should know...
...but of course the real answer is...
"When she doesn't put out after the second date!!!!"
Ok, so it wasn't really the answer i gave, but man when he asked it i was so close to crying it wasn't funny. If he only knew what I was really thinking...