BOP is a term for the multi gender attracted (m-spec) community. BOP is comprised of bi, omni, and pan/ply. Even if one doesn't identify with the labels mentioned, they can still be considered a part of the BOP community if they are attracted to two or more genders.
It is important to note however, the term BOP (Bop or bop) has another meaning and is used in a sexist light referring to someone who puts their body on the internet.
History
The term was coined by Tumblr user official-cisphobe on April 22, 2019.[1] The flags had previously been created by the same user on April 16, 2019.[2]