Related Clues:

• Insult response
• 'Likewise!'
• Snappy reply
• ''Have a good day!'' reply
• 'I'm not the only one?'
• "Have a nice day" response, and a literal hint to this puzzle's theme
• It's yourself as well that may sound like a plain spy
• It's no different to U
• ''So I'm not the only one?''
• Reciprocating response
• Essence of a Caesarean quote
• 'Et tu?'
• "I'm not the only one?"
• 'It's not just me?'
• "Right back atcha"