I guess the progression goes like this:

Donkey acts like an irrational donkey.
Hobbes gets angry at the donkey for behaving exactly as should be expected - like a donkey
Hobbes does something stupid and irrational himself.
Hobbes yells string of obscenities.
Dog runs to the corner and hides behind a chair.
Pregnant wife tells Hobbes he better not act this way when the baby comes.
Hobbes grumbles under his breathe, calls the dog over and rubs her belly.
Hobbes fires up a new game.