When walking by someone you have known for years, but have a grudge against them or you just don't like them. maybe that person came over to your mothers house for your family birthday dinner and you caught them masturbating in your family room. When you see this person coming towards you, as you walk down the street, you do not stop to say "Hello" or "Hey, hows your dog doing?" You simply wave and carry on.

When you eat dirt for the first time and leave your family to build a shack in the woods