If you churn milk you get butter; if you pound on your nose, you get blood--and if you stay angry, you get in trouble. Proverbs 30:33 (cev)

I've never made butter, but this makes sense to me because the nose thing and angry thing are true (so true, especially together).

Notice, too, verses 7-9. This is known as Agur's prayer. It seems to me to be very wise in its simplicity and understanding.