George Stephanopoulos was interviewing Donald Trump and was quizzing him on things he regretted.  Trump was wise to Stephanopoulos and talked only in general terms.  Trump told him that he knew there were things that Stephanopoulos regrets, too.  Stephanopoulos asked for an example and Trump nailed him.  You can watch the entire interview or if you wish to just watch this zinger fast forward to 18.40.