Yeah, my dad was a postman for 20+years, and he always used this funny helmet when he was riding the motor scooters. i found out why one day, when he came home from work and told me about this new dog on his route that attacked. This helmet sat on his head, not like modern helmets which fit around the head, and he had a quick release button on the strap. As he was riding the dog ran up and as it was about to bite his leg, Dad had grabbed the quick release and swung the helmet down and layed the dog out cold. That dog wouldnt go near him after that.

He taught me to deal with agressive dogs.
When I was at high school some of my friends told me aboutt a dog in a wrecking yard and how mean it was,So we walked past the 6 foot high fence. They wouldnt go near the fence but I walked up close and when the dog ran up and started I turned towards it and acted as if I knew it and called it over as if to play with it and wanted a game. That confused the hell out of it and I even got to give it a quick pat through the fence.
Its all in the bluff.