What humiliates Greg? What can you infer to this?

Usually his humiliation comes after he has done some wrongdoing and then is "outed" for it. Often the adults in his life and especially his brother Rodrick humiliate him regularly.

What sorta stuff did greg do?

For example, one time he asked, on his church's Christmas tree, for money. To see if anyone would fulfill his selfish wish, he shoveled the church walk. It turned out that by shoveling the walk he did a good thing, but the fact that he did it for a selfish reason was humiliating.

Selfish 6th grader then huh?

For example, one time he asked, on his church's Christmas tree, for money. To see if anyone would fulfill his selfish wish, he shoveled the church walk. It turned out that by shoveling the walk he did a good thing, but the fact that he did it for a selfish reason was humiliating.