Possible Clues:

• Cracking-up letters
• Texter's 'Too funny!'
• "u crack me up"
• 'omg 2 funny'
• "omg 2 funny"
• Big yuks, in text-speak
• “u r 2 funny”
• 'OMG, that is soooo funny!'
• Texter's "Too funny!"
• 'HAHAHA!,' in texts