Noting that: surprise parties can be organised and co-ordinated on Facebook between the friends and family of the person who will be subject to the surprise using private groups and private events. Potential party goers can be mined used the friends list of the subject, as well as the friends themselves.
Observing that: Facebook users seem to quickly get the hang of operational security (opsec) using the “public” medium of Facebook to mount a clandestine operation against one of the members of the same social circle.
Wondering whether: the Facebook algorithm either helps maintain that form of social/party planning opsec, or could possibly threaten it. For example, if someone accidentally makes a public post about the upcoming surprise party, does the Facebook algo suppress showing that post to the target (algorithmically, noting that a group with a particular social circle seem to be actively excluding one of the people you might expect to be in that circle), or might it prioritise showing that post to the target (algorithmically, on the the grounds that this person should normally be included in a discussions within a particular social circle and for some reason appears to have been excluded – which Facebook can spot and fix…)