How did Pudge Nichols get his name?

In Lorenzo Carcaterra's novel Gangster, Pudge Nichols is a hotheaded and ruthless servant to Angelo Vestieri. Pudge and Angelo meet when they are children, and after getting into a violent fistfight, they eventually become close friends. Pudge admires Angelo's ability to defend himself, though he initially almost kills Angelo with an excessive and bloody beating. An important accomplice to Angelo, Pudge Nichols is a similarly important character in the novel.
Pudge Nichols earns his name through his excessive eating habits. His tendency towards gluttony is addressed in the novel after Angelo invites him over for dinner:

"Pudge is coming for supper," Angelo said . . .
"Only if he comes with an empty somtach," Josephina said.
"Pudge loves to eat," Angelo said. "Ida said the only time he doesn't have food in his mouth is when he sleeps."

Just like many other fictional (and actual) gangsters, Pudge's nickname is comes from his appearance and his behavior. While not excessively overweight, Pudge Nichols acquires his endearing nickname through his constant consumption of food.