"bill, placard, thing posted," 1838, from post (v.1). Poster boy/girl/child "someone given prominence in certain causes" is attested by 1990, in reference to fund-raising drives for charities associated with disability, featuring child sufferers, a feature since 1930s.
权威例句
1. The current national poster child is a tiny, freckle-faced redhead.
现在的那个全国广告代言人个头不高,红头发,脸上有雀斑。
2. Washington looks like a poster boy for strength and athleticism.
华盛顿看上去是个典型的体魄强健、崇尚运动的人。
3. She went out with a Calvin Klein poster boy.
她和卡尔文·克莱恩品牌的一个广告代言人谈过恋爱。
4. This poster is offensive and degrades women.
这张海报冒失无礼,有辱女性尊严。
5. He is the poster child for incompetent government.