Kosher Candy

I just received this story by email:       

A Jewish man was in a supermarket in Thornhill, Ontario. He saw an obviously non-Jewish woman trying to get her young child to put down a candy bar he had picked off the shelf.
'Latrell, you put that down! It's not kosher!'
Intrigued, the young man decided to investigate.
'Excuse me, ma'am, are you Jewish?'
'No.'
'So why did you say that?'
'Why? I'll tell you why. 'Cuz I see all them Jewish mothers saying that to their kids -- and it works, so I decided to try it.'

I guess, after all, we’re supposed to be a “light unto the nations”… J

I wonder though, how is it that kids sense when we really “mean it”?