Unbelievable, We Were All Having a Good Time

UNBELIEVABLE! WE WERE ALL HAVING A GOOD TIME, AND THEN THIS GUY HAD TO COME ALONG AND SAY SOMETHING RUDE!

A black-and-white manga panel shows a stern-looking man beside a speech bubble complaining that everyone was having a good time until another guy arrived and said something rude. The joke is the exaggerated indignation, used as a reaction to someone ruining a pleasant conversation with an unwelcome comment.