A barber learns to shave by shaving fools

A barber does not shave himself

If someone shaves, I'm shaving too. It's something that kind of started and I'm waiting for someone to shave so I can shave. But I'm not going to be the first one.

Never ask a barber if you need a haircut.

Don't approach a goat from the front, a horse from the back, or a fool from any side.

A spoon does not know the taste of soup, nor a learned fool the taste of wisdom.