YSK of togethersmile.com, a free, anonymous photography website where users upload a simple picture of themselves smiling, to give another person a reason to smile today.
from /r/YouShouldKnow
togethersmile.com的YSK，一个免费的匿名摄影网站，用户上传自己微笑的简单照片，给另一个人一个今天微笑的理由。