know who's who(redirected from knows who's who)
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know who's who
To know details about or have connections with everyone or many people in a group. Usually used in relation to groups of rich, powerful, or famous people. I feel like a total fraud in this relationship. I mean, she knows who's who in the ultra-rich upper class of Maine, while I'm just a poor bartender who's going to community college. If you want to get ahead in this industry, you need to know who's who.