Related Clues:

• 'Boy, am I stupid!'
• Simpleton's utterance
• Sarcastic response
• 'Of course!'
• Comment made while slapping the forehead
• 'Like, I get it'
• Self-deprecating utterance
• 'How stupid of me!'
• 'How could I be so dumb?'
• 'What a dope!'
• ''Well, that's completely obvious!''
• 'Of course, blockhead!'
• "You don't say!"
• Forehead-slapper's cry
• "Of course!"