What does Proverbs 26:6 mean?

In Bible times messages were not delivered by email, text, or telephone. Designated people—messengers—were employed to deliver communications from senders to the recipients. However, not all assigned messengers were equally reliable. A person lacking common sense or morals (Proverbs 1:7) might be distracted, forget an important detail, deliberately change the message, or fail to find the recipient. Sending a message through a fool is as pointless as trying to walk after severing one's feet.

The metaphor of "drinking" is used in Scripture to imply something taken deeply, or in a strong manner. Trusting a fool with some important task is like calling violence down on oneself. It's no accident that God's requirements for teachers and messengers of the gospel include faithfulness (1 Corinthians 4:2). The message is important, and it cannot be dependent on unreliable, foolish people (Proverbs 3:33–35).