I tend to avoid overly-used, common proverbs, simply because I get tired of hearing them and I figured my kids would too. So when my oldest spilled some milk just now, I shrugged and told him to just clean it up. Then, in a silly voice, I said, "There's no use crying over spilled milk."
"Have I ever said that to you before?" I asked.
"I don't think so."
"It's an old saying to help people understand that once the milk is spilled, there's not much point in crying about it because crying doesn't unspill it. So, you might as well just get over it and clean it up."
My boy, nodding, "And that's just what I'm doing."
Thinking a bit more about wise sayings, my 11 year-old continued the conversation. "You know, a wise man once said, 'What's for dinner?' Wise men don't always say wise things."
We don't have a drum set, so there was no rimshot.
He also pointed out that one could say to another, "Wise things!" and still not be incredibly wise.
I have quite the philosopher/comedian on my hands.