There’s no single, agreed definition of what it means to be an asshole. It might include selfishness, arrogance, mean-spiritedness, or any number of other character flaws. You know asshole behavior when you see it. And if you’re normal, you’ve probably been one for at least a few minutes of your life. I would define an asshole as anyone who chooses to make the lives of others less pleasant for reasons that don’t appear productive or necessary.
Asshole behaviors: Changing the subject to him/herself Dominating conversation Bragging Cheating, lying Disagreeing with any suggestion, no matter how trivial Using honesty as a justification for cruelty Withholding simple favors out of some warped sense of social justice Abandoning the rules of civil behavior, such as saying hello or making eye contact