He sat in the room. He spoke a secret about his other friend to his friend in the room. The room was surrounded by 4 walls. He thought there was no way that his other friend would know he was gossiping about him. But alas the friend in the room he trusted leaked it out. The 4 walls did not keep his secret. Walls have ears.
We often think we can hide our words. But words once spoken from within you to the outside world cannot ever be locked by a safety valve. The effect of your words can virtually reach any destination. So be prepared to own upto the ownership of your words. Every spoken word is public. Walls have ears.
You may fully trust someone. But suddenly you find your trust has broken. You thought your trust was like a wall which could not be broken. Instead it turned out to be a wall with eager ears and even a mouth later. Walls have ears.