or poster boy; poster girl
1.
If someone is a ~ for a particular cause, characteristic, or activity, they are seen as a very good or typical example of it. (mainly AM)
Zidane has become the ~ for a whole generation of French-born youths of North African extraction...
N-COUNT: oft N for n
2.
A ~ is a young man or woman who appears on an advertising poster. (mainly AM)
She went out with a Calvin Klein poster boy...
N-COUNT