Related Clues:

• When repeated, gleeful student's cry
• "How could I miss that?!"
• "Everybody knows that!"
• ''I shoulda known that''
• ''I should have known that!''
• "Okay, I get it already"
• Slangy 'That's obvious!'
• ''That's no surprise''
• 'Duh!'
• "How stupid of me!"
• Brief acknowledgment
• Brow-slapper's syllable
• Word with a head slap
• 'Who doesn't know that?!'
• Part 1 of today's quote