It's rude to touch people's animals without permission.
As James was waiting in line, he saw that the woman ahead of him had a large dog on a leash.
James, a dog lover, wants to pet the dog.
James asks the dog's owner if he can pet it.
James leans forward and tries to pet the dog's head without asking its owner.
The dog's owner tells James the dog only likes to be petted on its butt, so James pets it correctly and the dog licks his hand.
James accidentally brushes a painful rash on the dog's head, causing it to bite him.