poster child
noun /ˈpəʊstə tʃaɪld/
/ˈpəʊstər tʃaɪld/
(also poster boy, poster girl)
(especially North American English)- a child with a particular illness or other problem whose picture appears on a poster advertising an organization that helps children with that illness or problem
- (often humorous) a person who is seen as representing a particular quality or activity
- He is the poster child for incompetent government.