Related Clues:

• OED initialism since 2011
• Typed guffaw
• "U slay me!"
• 'Haha, u r hilarious'
• 'That cracks me up!'
• "How hilarious!" in chat rooms
• "I'm cracking up," in a tweet
• Roaring online?
• Titter on Twitter
• "That's funny" online
• Texted titter
• 'UR so funny!'
• Texting 'ha-ha!'
• I.M. chuckle
• Tweeter's titter