Possible Clues:

• "I can't believe I missed that!"
• "I think we all know that!"
• 'That's, like, preschool level'
• "Thanks, Captain Obvious"
• "Well, that's obvious"
• 'Thanks, Captain Obvious'
• 'Obviously, silly!'
• Head slapper's remark
• 'I should know that!'
• 'OB-viously!'