Some people have a tendency to give wrong answers in casual conversation.  Not like

Person 1:  Who did you vote for?
Person 2:  John McCain.
Person 1:  Wrong answer!

More like

Person 1:  Hey, what's new?
Person 2:  Pretty good.
Person 1:  Wrong answer.

It usually happens because of a miscommunication or a misunderstanding.  But sometimes it's also because people get nervous in social situations.  For me, it only happens when I talk to specific people, who, for whatever reason, make me nervous.  I keep seeing this one guy in a social setting (I don't know how to make that sound less gay) and I keep saying the wrong things.  This was our most recent conversation: 

Guy:  Hey Dave, how was your holiday?
Me:  Hey, you too.

I thought he said, "Have a good holiday."  It was more of a conversation-in-passing, and once I realized my answer didn't match up with his question, it was too late to go back to him and say, "I misheard what you said.  My holiday was great.  How was yours?"  Sometimes you just need to give the wrong answer and move on.