The fight against the Colossus in God of War II. A giant eagle steals Kratos's powers and brings a wonder of the ancient world to life with blue lightning. By sheer determination and what's left of his powers, Kratos breaks its arms in a water wheel, launches a boulder the size of a house at its head and blinds it. He punches it in the face with its own severed hand, then slashes his way inside, and destroys it, leaping out of its mouth. Ladies and gentlemen, that was the punchline. To rant at the gods. Thanks to this, he fails to avoid being squished like a bug by the hand of the falling giant.
During the battle against Hercules, Hera, quite clearly drunk off her ass, tells the two blood-soaked bruisers, as they're about to beat each other to death, "You boys play nice!"
Kratos's first words to Hermes are, "To catch a fly from the ass of Zeus is not worth my time, Hermes." Later, Hermes, upon being killed by Kratos, explodes into a swarm of flies. And Kratos smishes one.
The silly costumes in each game are an excellent laugh. Examples:
God of War has the Chef of War costume, where Kratos wears a chef's hat, white coat and wields a cleaver.
God of War II sees Kratos as the Cod of War, where he dresses in a giant cod costume.
God of War: Chains of Olympus gives access to the Mime of War, where Kratos wears mime makeup and goes unarmed, killing his foes by simply swinging his arms in their direction.
The scene where Kratos killed David Jaffe while congratulating the player.
One of the potential bits of commentary during the sex minigame in God Of War III hangs a humorous lampshade on the provocative scene:
Nymph: [fondling her partner while watching Kratos off-screen] Wow, this really is for mature audiences only!
Other nymph: Parents shouldn't let their kids watch this!
The sex scenes in each game are funny on their own, but adding to the joke is the fact that they grow progressively over-the-tope. In Ghost of Sparta, the scene starts with Kratos grabbing two prostitutes; then, as the player inputs commands correctly, the screen starts shaking increasingly violently, and more and more prostitutes will come running to join in. When Kratos is done he will have seemingly pleasured eight or so partners... at the same time.
The Seen It All half-rotted guy Kratos encounters at the entrance to the Temple of Pandora in the first game. He sounds positively bored when Kratos comes by, but goes through the whole ritual because its his job to open the gate for anyone who want to try it... and then burn the remains of the idiots who fail.