On the Facebook platform, the phrase in question describes a custom audience setting used when posting content. This setting allows a user to share a post with all of their friends except for specific individuals they designate. For instance, a user might post photos from a surprise party but exclude the person for whom the party is being held to maintain the surprise.
This selective sharing functionality provides a significant level of control over content visibility. It balances the desire to share broadly with the need to maintain privacy or avoid specific individuals from seeing certain posts. This capability has evolved in response to user requests for greater granularity in managing their online social interactions and content dissemination.