Related Clues:

• 'I am an idiot!'
• "I'm such a klutz!"
• Play-___ (kids' art medium)
• Exclamation popularized by “The Simpsons”
• ''I knew that!''
• It's listed as "(annoyed grunt)" in "The Simpsons" scripts
• Play-___ (kid's clay)
• Play-___ (kids' clay)
• 'Obviously'
• Play-___ (kid's stuff)
• [Facepalm!]
• First note of major scale in music
• First of the series at 17 Across
• It begins the tonic solfa
• First note of tonic solfa