喜歡照鏡子的人，只要看到有玻璃能照到自己的樣子，就會忍不住過去照一照。于是，商店的櫥窗、停靠路邊的汽車窗玻璃都成了假想的鏡子。

A window looker refers to someone who compulsively looks into windows of buildings, stores or parked cars to check out their hair, their teeth, and everything about their appearance. People who usually behave like this are either having a strong sense of inferiority or having too much self-confidence.
Window looker指看到建筑物、商店或者停泊車輛的窗玻璃就忍不住想要照一照，檢查一下自己的發型、牙齒，或者整個外表狀況，我們可以稱之為“照窗族”。經常有這種行為的人要不是特別缺乏自信，要不就是太自戀。

For example:

Dave, don't be such a window looker. Your hair looks the same as the last time you checked, 30 seconds ago.
戴夫，別照了。你的頭發跟30秒前剛剛看過的時候一樣，沒啥變化。

（中國日報網英語點津 Helen）