Possible Clues:

• 'I wasn't the only one?'
• "Right back atcha"
• ''Have a good day'' reply
• Reply to 'Have a nice day'
• "And here I thought I was the only one"
• 'And here I thought I was the only one'
• Awkward response to 'Happy Birthday!'
• It's yourself as well that may sound like a plain spy