You shouldn't scream in public.
Tim sees his friend across a busy street with many people around.
Tim wants to get his friend's attention.
Tim waves his arm until his friend notices the movement and recognizes Tim.
Tim yells loudly so that his friend notices him across the street.
The people on the street aren't bothered by Tim, most don't even notice him.
The people on the street are annoyed by Tim's loud yelling.