It's no secret that joffrey is big on public humiliation and cruelty, but, where does he get it from?
1. Publically humilate's Sansa
2. Makes Sansa look at disgusting things
3. Murders and torchers whores
4. Kills rabbits for fun
5. Humiliates Tyrion at Tyrion's wedding
6. Humiliates Tyrion at Joffrey's wedding.
7. Asks someone to chose their tongue or hands
8. Changes his verdict at the last second to kill Ned in front of everyone
1. Tywin Lannister, man who rules by fear and creates an image of menace about himself
2. Tyrion (Notice how he publically slaps Joffrey often, in front of people Joff respects, such as the Hound.)
3. Arya, remember how she humiliated him by the river.
4. Robert Baratheon, always drunk, and unruly. Probably a humuliating life.
5. Being illegitimate, he must have seen a huge difference between himself and his father, and it made him uncomfortable.
It just seems odd that Joffrey's antics should be so concentrated on one thing, public humiliation. He's not greedy, or a slob, a drunk, doesn't partake in whores, or spend too much money, etc. But he's cruel when it comes to something he can see and feel in other's faces, he has that in spades.