Good one! Very funny!
Cats show disapproval by smacking their paw on the nose of the other cat. That's why we are advised to do the same to our own cats when they are being naughty. I have a very mischievious and active kitten and my older cat will actually hold her paw on his nose when he gets out of control.
The cat on the right is showing dominance by not removing eye contact when the other cat retaliated to the accidental scratch. Usually it's the cat left in the room (the dominant cat) after the other cat has left, that is the one that has caused all the trouble - just sitting there looking very innocent. When cats stare each other out it spells trouble.