A microexpression is a brief, involuntary facial expression shown on the face of humans and chimpanzees when one is trying to conceal an emotion. They consist of and completely resemble the 6 universal emotions: disgust, anger, fear, sadness, happiness, and surprise.Detecting such things can be disturbing, as when someone keeps making disturbing jokes.
When he makes impromptu quips
the mask of kindness often slips
and a scowl crosses his lips.