Creatures of habit I guess

I was at a coffee shop tonight waiting for my friend to show up when I received a phone call.  It was this girl calling about an ad I put up on allMSU for a textbook I've been trying to get rid of.  Unfortunately for her, I had already committed to selling to it someone else.  I ended the conversation by saying "well thanks for calling, have a great night."  Her reply was "okay thanks, talk to you later."

How often do we say things and have no idea what we're talking about?  Obviously, there's very little chance she's going to talk to me later because she doesn't know me and really has no reason to ever call me again.  Every now and then I'll accidentally say "you too" when someone says something to me.  A couple weeks ago I was at Subway and the guy who makes me a sandwich at Subway and says "thanks, enjoy your sandwich."  

"Thanks, you too!"

I bet he didn't like me very much when I said that.