Possible Clues:

• 'Mmm-hmm. If you say so'
• 'Yeah, really'
• 'Yeah, that'll happen'
• Some tennis strokes
• Words said with an eye roll
• "That's unlikely"
• ''That's not gonna happen''
• "Pshh, yeah, sure"
• Scoffing comment
• 'You expect me to believe that?'