This expression means, “I’ve completely blended in with my surroundings and you can’t see me.”
Fun Fact: It’s not just peanut butter. Your dog’s hearing is so sensitive that we can hear a knife cutting lunch meat.
Please make a sandwich for me too!
Fun Fact: Your dog has very sensitive hearing. How sensitive? So sensitive that we can hear a knife spreading peanut butter. So please give me a piece of your sandwich!
(Photo via Wikimedia Commons licensed under Attribution-ShareAlike 3.0 Unported. This image is cropped from the original.)