Possible Clues:

• 'Hilarious!,' online
• '2 funny!!!'
• Response to being slain, in texts?
• Texter's 'Hilarious!'
• Texter's guffaw
• "u slay me"
• 'That's hilarious,' in Internet-speak
• "That's hilarious," in Internet-speak
• It's somewhat stronger than LOL
• Texter's response to a hilarious joke