Possible Clues:

• 'r u for real?'
• "Really?," in textspeak
• "R u for real?"
• "4 real?!"
• '4 real?!?'
• "Rly?"
• 'ur joking, right?!'
• 'omg 4 real?'
• "R u kidding me?"
• "But rly tho??"