Possible Clues:

• "This works like a charm!"
• Cheeky comeback to "How did you do that?"
• 'Don't worry about how I did that'
• Eyeroll-inducing response to 'How did you do that?'
• 'How'd you do that?!' response
• Illusionist's coy explanation
• Theme song of 'The Doris Day Show'
• Unhelpful reply to 'How did you do that?'
• "I can't explain how I did that"
• Unhelpful response to "How did you do that?"