You didn't even have to live thru the 80s to know this has been around longer than any Gen Z has been alive, you just need to watch any 80s media to see an example.
The people that did it as teens in the 80s/90s are just freaking out theyre on the other end.
They had bad connotations when they did it, but they did it so much it became normalized. So when they get it, they assume they're being called stupid, when the kid just doesn't give a duck one way or the other.