My grandfather had one of these in his workshop... when I was little I never understood the joke, and it had to be explained to me repeatedly. I thought it was the weirdest thing, glad to know that others exist out there.

How clever, Reminds me of a sign I saw a sign once when I was living on the San Carlos Reservation in Arizona, it said "TEENAGERS!: Tired of Mom and Dad harassing you? ACT NOW!!, Move out, get a job, pay bills, while you still know everything!"

^ that would be this.

I had a coach in High School that had several things in her office with this on it...and she taught all of her teams this cheer:

Get to it and at it
and at it and to it
and to it and at it again!

If you don't get to it
while you're at it
you'll never get it again!