Cryptidboy is a term which describes one's gender as "outwardly identifying as a man, and inwardly as a cryptidlike entity", such as mothman, yeti, jersey devil, etc.
The feminine equivalent is Cryptidgirl.
History
Cryptidboy was coined by Tumblr user heartfelt-angel on June 10, 2021.[1]
Flag
The flag was created by the same user on the same date. It has no confirmed meaning.
An alternate flag was created on August 5, 2021, by FANDOM user Mushiifrogg.[2][3] It has no confirmed meaning.