"Shut up, Bobby Lee," The Misfit said. "It's no real pleasure in life." (142)
This is the reversal of what the Misfit said earlier about meanness being the only pleasure in life. What he's just done – shooting the grandmother dead – merits being called "mean," yet apparently he doesn't feel good about it. Perhaps he's fallen into complete despair, since now there's nothing left to give him pleasure. This would mean that killing the grandmother seriously affected him. Or perhaps it's the beginning of his transformation into a good man. Perhaps both.