a misspelling of the contraction could've

From STEM, an abbreviation short for "Science, Technology, Engineering and Mathematics", a STEMlord is a pejorative term for a particular kind of person who has studied in these areas at university or works in these fields who holds a pretentious, condescending attitude to anyone who has studied in any other fields, particularly the Arts and Humanities. They typically believe themselves to be more "intelligent" and "rational", while generally remaining incredibly ignorant outside of their areas of expertise and having the charisma of a rotting pig's backside.

How the uneducated say 'could have'

A common misconception among idiots who go by their ears rather than their brain. The real way to say it is "Could HAVE", i.e. "I could HAVE gone to the party", rather than "I could OF gone to the party".

It's a common mistake, generally caused because the phrase "Could have" is said so quickly that it is conceived as "Could of", but that's wrong.

"Should of" is the exact same but slightly less common mistake.