Ask the kid if a (chloroform-soaked) rag smells like chloroform to them.
I think Kenny has had some success with food, but I think that was in case of excessive complaining.
Sam Saeger in particular has an excellent "teacher" voice that is useful for dealing with expressive children and/or obnoxious CSU members.
"Yes, I know there are a lot of trees... that tends to happen when we're in the woods..."
So hard to be sarcastic-polite for an entire afternoon...