A shortening of the word Serious.
"this guy cannot be seir."
"is this guy seir?"
Seir (adj.)
Pronounced: SEER
A modern slang term equivalent to the word "serious," it can be used to express a high level of importance or gravity in a situation or statement.
(Def not written by chatgpt)
"you cant be seir."
"are you being dead seir?"
"being seir, im in alot of trouble"