I like calling it 'ee-gee-oh'. Why? Because I used to play a game called Gunz (A third-person shooter), and one of the reasons why I quit was because of the ego. It used to flourish with exceptional players that didn't ego. Now, pretty much everyone does it. I learned the terms like 'ezpz', 'ezasfck', 'dropped 15-0', all sorts of other insults thrown at each other in clan wars and in public games.
If you don't know what ego is, then here's a quick definition for you: an inflated feeling of pride in your superiority to others.
I've been taking some Psychology courses as well, and as psychologist Jean Piaget says, young children are egocentric, is defined as a) the incomplete differentiation of the self and the world, including other people and b) the tendency to perceive, understand and interpret the world in terms of the self. This does not mean that they are selfish, but that they do not have the mental ability to understand that other people may have different opinions and beliefs from themselves.