When someone is so stupid like Keemstar they become "Keemstar Stupid"
"You are really Keemstar stupid God damn."
The 4th component of the psyche that is responsible for causing one to make poor decisions.
I meant to send my curse-filled email response to only one person but my stupid-ego made me hit "reply all."
A horny, prostute obsessed asshole!
Jacob is such a stupid pussy!
A D&D (or other similar system) character who uses their chaotic alignment (usually chaotic neutral) as an excuse to do whatever they want, even if it's obviously a lethally bad idea, will piss off the other players, is extremely out-of-character, or a combination of the three.
DM: You see a large corridor with a desk at the end.
Player 1: Whose desk is it?
DM: The nametag on the door behind you said "Planetar General".
Player 2: I shit on the desk.
Player 1: Dude no don't you'll get us killed.
DM: Are you sure you want to do that?
Player 2: My character is chaotic neutral, and as such would do this very stupid thing for the sole reason of causing chaos, regardless of consequences or how anyone else would react.
Player 1: More like Chaotic Stupid.
When a dude gets so sexually aroused he can't think straight.
I get so Goober Stupid when she pulls out that big'ol ass. I can't think about anything but butt.
Involuntary cringe that comes when someone says something incredibly stupid.
Person 1: "...so that's why i think Elvis is still alive."
Person 2: *stupidity cringe* "Dude, no."