“Oregano” is slang popularized back on Reddit, on a community page called r/AntifaStoneToss, focusing on making disruptive edits to comics made by StoneToss, a cartoonist who frequently makes comics with nazi rhetoric.
back when the page was starting out, out of curiosity, people would often make comments asking to explain or show the contents and nature of the original. while i don’t know the exact details, i know that what followed is that people would often replace “Original?” with whatever other wording starting with an O that they could think of.