Possible Clues:

• ''Well, that's obvious!''
• Stupid response
• "I'm not stupid, y'know"
• ''How stupid of me!''
• "C'mon, too easy!"
• Sarcastic retort
• "Like I didn't know!"
• "How dumb can I be!"
• 'I'm such a dope!'
• ''No kidding, stupid!''