... to bite you in the ass. Or, the moment you realized no matter how well you teach your kids it's ultimately your behavior that is the teaching example.
The sweet tender fruit of my womb was behaving in a particularly obnoxious way; that way that only your own kids can do to irritate you beyond your breaking point. They come pre-wired for that, you know. It was at this point, in my utter exasperation I blasphemed. My son stopped dead in his tracks calculating his next move. I was expecting an apologetic gushing, not the firm reprimand that followed ...
... "You said the Lord's name in vain! You broke a commandment! Now you have to go to confession!"
Schooled by a seven year old. Sigh.