Possible Clues:

• "Well, of course!"
• 'Um... Did u srsly not kno dat?'
• "No __!"
• 'I *finally* got it!'
• Response to an obvious statement
• 'I'm an idiot!'
• Forehead-slapping interjection
• 'I thought that was obvious!'
• 'What a dope I am!'
• 'Of course, you idiot!'