Aren’t You Going to Say Something Nice About Me?
 
A business associate used to humorously illustrate this point.  He would approach a coworker and pay them a sincere compliment and then would pause and not say anything for a moment.  Then he would look them in the eye and say, “Now aren’t you going to say something nice about me?”  Through his antics he made the point that we love to be complimented but most of us don’t return the favor.