When you muck up real bad, and look like an idiot. An undeniable idiot in front of many people and all they can do is give you that look, the "what the fuck!?" look. The 'damn this kid's a dumb ass look". Too stupid to function...
Teacher: Ian, name the world's largest country?
Ian: Ahhhh...Popeyes chicken..?
Teacher: (The what the fuck did he just say look)
Class: (damn, this kid is stupid look)
Diagnosis: L's syndrome