Possible Clues:

• "Boy, am I dumb!"
• 'Duh!'
• 'Boy, am I a dope!'
• "Ha! What was I thinking?!"
• "I am a fool!"
• 'D'oh!'
• 'I'm such a dummy!'
• “Whatever was I thinking?”
• 'Wow, I am dumb!'
• "Wow, I am dumb!"