The Question and Answer section for One Flew Over the Cuckoo’s Nest is a great resource to ask questions, find answers, and discuss the novel.
McMurphy is rebellious, fun loving, and confrontational. He's also charming, as well as quite the manipulator.
In context, psychopath is defined on Page 13 in the following way;
"Now they tell me a psychopath's a guy fights too much and f****s too much, but they ain't wholly right, do you think?"