This little guy again.
The big walk every day is to and from the park. At the park, there is romping. Between here and the park: Road. Cars. Busses.
Edgar fears and loathes a bus. As a puppy, he would scurry away, tail tucked under his body, whenever he heard one coming. Now he's braver. A little older, a little wiser, a little more experienced with busses. His tail drops, held in a gentle u-curve behind him, but it does not retreat beneath him. He will approach a bus if he absolutely must.
The problem for Edgar is the noise that a bus makes. We make a noise, a "psst" noise, when we need him to stop what he's doing right now. It means, "I am going to ignore you for the next two minutes."
Edgar lives on attention. He is made to be attended to. To be ignored is the worst punishment he can imagine.
A bus makes a huge version of this noise, a great, sighing pneumatic hiss, as it settles into a stop. So a bus is not just a huge and potentially angry metal dragon. It is a dragon that is mad at Edgar personally.
Earlier this year he became hesitant to enter certain crosswalks, because he had witnessed men with hissing sticks, painting lines in those crosswalks. As is the way of dogs, he remembered the hesitance, long after he had forgotten the sticks.
I had a dog growing up that was this way about frogs and frog-shaped things. As a very small puppy he encountered a toad, popped it in his mouth, spit it back out, and sat down very hard. Toads taste bad. The next year, another toad, but by this time he had forgotten the details of toads. He hopped back and forth, growling and barking, putting on an impressive threat display for this ignorant amphibian.
We tried to explain to the dog that a toad was only a problem if he tried to eat it, but he persisted, putting on a similar display for any sufficiently frog-like garden ornament he encountered on his daily walks.