I don't know what that means
A fancy way to say you’re too dumb to understand and you want others to think you’re smart. You say it with a fake confused face like you're a detective solving a crime.
"I don't know what that means" after I asked what 'ghosting' was.
"I don't know what that means" when I asked what 'flexing' was.
"I don't know what that means" when I asked why my friend called me a 'dumbass'.